PackageManager: Move routine to write local pkg list to Location struct

PackageManager: Move routine to write override in Location struct

Trivial: Remove redundant cast

PackageManager: Move Location-specific code to Location type ...

Because having a nested function that looks up an index in a field
and goes through this indirection all the time doesn't seem like
the best design anymore.

Trivial: Document PackageManager.Location, add attributes

Overrides: Make it clear that only VersionRange can be overriden ...

The code was always assuming overrides were VersionRange,
as trying to do 'dub add-override' would call 'Dependency'
constructor with a string, which forwards to VersionRange.fromString.
However, when using dub as a library, this assumption was much less obvious,
notably because the fields are public.
With this change, we make sure library users do not misuse overrides.

Use std.sumtype for PackageOverride too ...

Like Dependency, we only were using one of those two fields,
but it was not readily obvious before, and we relied on one
of them being empty to read the other one.

Trivial: Pass a Repository to loadGitPackage

Remove `Dub.updatePackageSearchPath` ...

This function was essentially two functions: One when an override was set,
another one for the common case. However, the function is private,
and the number of call sites is limited, so it's better to inline
the call at the caller site. Once that was done, it became obvious
it only ever has an effect once, when the Dub instance is constructed,
as we don't modify this environment variable.
Thus, we can inline it in the constructor, and remove the dead branches.

Trivial: Update comments on PackageManager ...

The previous comments were a bit misleading.

Rename private packagemanager : Repository to Location ...

Avoid ambiguity with dependency : Repository and matches PlacementLocation.

Deprecate duplicated enum LocalPackageType -> PlacementLocation ...

Two enums, both have the same values, in the same order.

Keep logging functionality out of the public API as requested in https://github.com/dlang/dub/pull/2124#issuecomment-813016939.

Output improvements in package management ...

(dub fetch and dub remove)

New logging module - initial functionality ...

The new module replaces dub.internal.vibecompat.core.log by using the
same function names, but implementing colored output and the left
fixed-width tag. Overloaded functions are provided to output colored
text.

Still missing initLogging() and non-TTY stdout/stderr detection

Unify package path in a single PackageManager function ...

The idea is that PackageManager should be responsible for packages on the disk,
and the first step to do that is remove the leakage of path happening in the Dub class.

Move PlacementLocation from project to PackageManager ...

PlacementLocation define which local path is used for storing packages.
It has nothing to do with project (it's not even used there),
and should be contained inside PackageManager, even if currently
quite a few details are leaking all over the place.

Deprecate `PackageManager.loadSCMPackage` & other `Dependency`-related refactoring (#2312) ...

* Trivial: Take a nested function out of a foreach loop

* Deprecate PackageManager.loadSCMPackage's Dependency overload, use Repository

We're moving away from using `Dependency.m_range` to store the git ref,
and the `Repository` type has already been updated to include the information,
but some places still read it from `m_range`, including this one.

* Trivial: Forward Dependency's string ctor to VersionRange ctor

* Trivial: Simplify comparison with `VersionRange.Invalid` within `VersionRange`

PackageManager: Use PackageRecipe, not JSON, for dummy object

Deprecate once-called redundant getLatestPackage ...

getBestPackage present a more generic interface,
as long as we feed it Dependency.any.

Merge remote-tracking branch 'origin/stable' into merge_stable ...

Conflicts:
	source/dub/dependency.d

Avoid needless string concat in log calls

Also use strict version matching for cached packages when determining the need to fetch a dependency. ...

Fixes #2262.

Also let getBestPackage use VersionMatchMode.strict for managed packages.

Match versions of cached packages exactly. ...

Uses exact version matching instead of SemVer matching for cached packages to enforce exact matches for SCM based dependencies in particular.

Replace deprecated keyword `body` with `do`

Support dependencies as git url with exact commit (#1798) ...

* Support dependencies as git url with exact commit

* Compare hashes for SCM

Fix #1040 - dub run <package>@x.y.z ignores the specified version

Deprecate compatibility overload in PackageManager

Clean up PackageManager handling of search path ...

The PackageManager is a complicated beast:
it is responsible for handling the local caches where downloaded
packages are stored, including looking up a specific version of a specific package.

One feature that stood out while going over the code was the ability to disable
the default search path.
After looking up inside of Dub more, it turns out that this feature is exclusively
used when dub is called with the '--bare' option.

However, when this happen, a special constructor of the Dub class is called,
one that calls the 'PackageManager' constructor with 3 dummy arguments,
and rely on a boolean being set to avoid those 3 dummy arguments having any effect.
This ends up with effectively providing the ability to toggle the ability to
search default search paths in theory, but in practice the dummy arguments
means that it wouldn't work, nor is it actually needed.

Instead, a special argument for the single-search path approach is provided now.
In order not to break library users, the public symbols have been deprecated,
but their usage still works.
Note that some symbols are deeply entangled: for example, 'Dub.m_overrideSearchPath'
being non-empty means that 'PackageManager.m_disableDefaultSearchPaths' is 'true'.
It also means that 'PackageManager.m_repositories' is unused (and can be empty).
Hopefully removing the ability to toggle the default search path will allow
us to simplify things and make 'PackageManager.m_repositories' the only way
to specify whether or not the default packages search path are used.

Note that additionally to the changes aiming to deprecate 'Dub.m_overrideSearchPath'
and 'PackageManager.m_disableDefaultSearchPath', an unused constructor of PackageManager
has been deprecated.