Respect skipRegistry value from configuration files ...

Currently, the skipRegistry value in configuration files is ignored,
the final value is either the one the user passed on the command line,
which is the intended behavior, or the value `none` if the user didn't
pass a --skip-registry argument.

This commit fixes this by introducing the new value `default_` to the
SkippackageSuppliers enum to know when the user didn't pass the
skip-registry argument and the value should be taken from the
configuration files.

Signed-off-by: Andrei Horodniceanu <a.horodniceanu@proton.me>

Improve the output when the subcommand is not found ...

Sort subcommands based on similarity.

Change all references to std.file in commandline to FQN ...

This makes it more visible where std.file is used, as we want
to reduce the number of places we do I/O, and as we have
two ways to do I/O in Dub.

CLI: Simplify control flow by bundling two operations together

Move Package.findPackageFile to PackageManager, mock ...

Moving it to PackageManager allows us to call PackageManager.existsFile,
allowing us to mock a lot more things.

Clear up unprinted deprecation for overrides ...

This code should have triggered a deprecation, however it didn't
get printed for some unknown reason. Turning on '-de' leads to seeing
it. The fix is fairly straightforward and doesn't affect the code.

CLI: Slightly reduce memory allocations ...

By improving commandNames to only allocate once (the array call) instead
of many times (once per CommandGroup + join call),
as well as removing a call to commandNames and using a simple getter.

CLI: Simplify extractCommandNameArgument

Trivial: Fix #2774 - Color codes on windows terminal

Do not allow for removal of subpackages ...

Because it can mess up the system quite dramatically.

Adapt PackageManager.get[Best]Package to PackageName API ...

This paves the way to be able to automatically return subpackages.

Remove PackageName alias this to toString ...

The alias this was originally added to make the transition
less painful, however due to an overload resolution bug,
it makes it harder at the moment, as thje compiler prefers
calling the deprecated `string` overloads over the
`in PackageName` ones. So remove it and a few hacks along
the way.

Adapt PackageSuppliers to PackageName API ...

Since we recently did a semi-breaking change to PackageSuppliers,
now is the time to do it again (they will be in the same release).
Again the same logic applies: it's only a breaking change for those
inheriting from PackageSupplier, not those calling it,
and there is likely not a lot of people doing either out there.

Trivial: Adapt fixPathDependency to PackageName API

Improve Dub.fetch API ...

The API was not ideal, as it meant the caller has
to be a bit repetitive in what it was doing:
- defaultPlacementLocation should be used when possible;
- A library user would most likely want FetchOptions.none;
- The most simple use case would be 'dub.fetch(pkgName)',
  meaning get me the latest version of pkgName, as is used
  by the tools fetching code;
All of this is now supported, in addition to a transition
to using the PackageName API.

Introduce PackageName, to fully type a package name ...

Package names being passed around in the Dub codebase are string,
which is problematic as it suffers from validation / semantic issues.
Validation because we cannot impose restrictions on characters
or length easily, and semantic because some functions expect a main
package while some would accept a subpackage. Introducing a type
will remedy both those issues.

Deprecate system flag for registration, use cache instead ...

The system flag likely predates the global 'cache' option.
Logic dictates that 'dub add-path --cache=system' should behave
the same as 'dub add-path --system' but that is not the case.
However the PackageManager already has the right API in place,
so it is just a matter of deprecating the layers in front.

fetch: Support multiple arguments, projects, recursive fetch ...

Dub fetch was overly limited for no reason: Since we migrated from
`--version` to `name@version`, there is no reason to only allow one
argument, multiple packages can be fetched. Additionally, it could
be useful to fetch a package's dependency without building it,
which the command now supports.

Provide a consistent experience when interacting with dub fetch ...

'dub fetch doesNotExists' and 'dub fetch doesNotExists@1.0.0'
were behaving differently, both when they succeeded and when
they failed. Making them consistent was just a matter of deleting
a few lines of code, allowing us to also remove a branch.

Fix #2706: Dub run ignores locally registered packages ...

The code was overly complicated and failed to do what it intended.
If a version was provided, it would always call 'fetch' even though
getBestPackage would have returned something.
Assuming that sub-packages are always present is also not working,
as the following would fail:
$ rm -rf ~/.dub/packages/vibe-d && dub run vibe-d:data
    Warning Package 'vibe-d:data' was neither found locally nor online.
The new code is both shorter and simpler, taking advantage
of the various improvements made to the APIs over the year
(for example, getBestPackage with VersionRange.Any does the right thing).

CommandLine: Make better use of UserPackageDesc

CommandLine: Rename PackageAndVersion, slightly refactor, document

CommandLine: Store a VersionRange, not a string, in PackageAndVersion ...

Typing this parameter means that places know they have a valid
version on their hand as opposed to a string everyone need to
validate and verify.

Deprecate Project.packageManager ...

There is no reason to expose the PackageManager through the Project.
In fact, the only two places it was used were in generators,
where the PackageManager was stored but never used.
The generators arguably should not have access to the PackageManager,
as all the Packages should have been loaded and handled to them
before the generation starts.

Remove fallback to ~master on dub fetch, fix #2679 ...

The retry does not make sense, as one cannot add a package
to the registry without a release version.
It is also not in line with Dub strategy, as we are trying
to reduce the usage of branch dependencies.

This also fixes issue #2679 which pointed out the error message
was sub-par. The API of the registry seems to have changed and
we now get `null` instead of `undefined`, leading to an error
inside the JSON module instead of the enforce being triggered.

Trivial: Remove dead existsFile import ...

It is not used in this function.

Remove unused iterateDirectory(string) ...

It was actually unused, because al the call sites were doing a useless
round-trip from NativePath to string to NativePath.
There is no need for it anymore so we can just remove it to avoid
this kind of mistakes in the future.

Fix issue #2190 - windows: dub won't run if TEMP is unset or empty

interactively query for license, suggest SPDX licenses (#1902) ...

Co-authored-by: Martin Nowak <code@dawg.eu>

add --deep flag to `dub build` ...

Allows to build all dependencies of a static library