CI: Reduce dependency on std.path / std.file in one unittest ...

This will make migrating to the abstracted IO much easier.

Look up `dub.selections.json` files in parent directories too (#2272) ...

* Look up `dub.selections.json` files in parent directories too

In case the root package directory doesn't contain a `dub.selections.json`
file, look in parent directories too and load the first (deepest) one.

This allows using a 'central' `dub.selections.json` file for a repository
containing multiple dub projects, making it automatically apply to all
builds in that source tree if located in the repository root directory
(unless a local `dub.selections.json` overrides it).

Such an 'inherited' selections file is never mutated when running dub for
a nested project, i.e., changes are always saved to a *local*
`dub.selections.json` file.

Merge remote-tracking branch 'upstream/stable' into merge_stable

update version to v1.38.1-rc.1

LDC: Don't keep around temporary object files for static libs (#2690) ...

* LDC: Don't keep around temporary object files for static libs

This was a workaround for older LDC versions. Since LDC v1.25,
`-cleanup-obj` implies that the temporary object files are placed
into a unique temp directory (per compiler invocation), so that
object file collisions across parallel dub invocations cannot happen
anymore.

Trivial: Remove internal deprecations ...

Neither commandline not dub.internal are part of the public API for the library,
hence those deprecations were unnecessary.

Merge pull request #2928 from Geod24/mlang/Fix2830 ...

VersionRange: Always output minor version for ~> and ^

Tests: Implement the ability to mock the registry too ...

So far tests have limited themselves to the local state,
but we want to expand them to test the behavior of dub
when fetching packages, so we need a convenient way
to add packages to the registry.

FSEntry: Set a default time for all entries ...

Otherwise we are not able to write the entries in a Zip file,
as we get an exception from std.zip.
This is a workaround and a proper fix would be to implement
a Clock system.

Work around file locking dependency in PackageManager ...

The `dub.internal.utils : lockFile` function does not land itself to mocking quite well,
as it exposes a struct containing a `std.stdio : File` instance.
The path of least resistance, for now, is to access `store_` directly from
TestPackageManager by overriding `store`.

Do not use `Package.storeInfo` in `PackageManager.store` ...

`Package.storeInfo` does IO directly which conflicts with our
dependency injection approach. Instead inline the code and
use `this.writeFile` directly.

ToolchainRequirements: Handle '*' while parsing PackageRecipe ...

PR 2926 added the possibility that '*' is serialized to PackageRecipe
instead of '>=0.0.0' but we need the parser to handle it.

VersionRange: Always output minor version for ~> and ^ ...

Dub was correct in outputting only the major version,
however this can lead to some confusion for users
as pointed out in #2830. Accepting ~>5 but only exposing
two states (~>5.0 and ~>5.0.0) will hopefully make
things a bit more obvious.

Fix #2901: VersionRange.toString() doesn't handle >0.0.0 ...

The `VersionRange.toString` method was not ideal and dropping
this rare case. A tiny improvement that was also done in the
process is to give higher priority to `matchesAny` so that
we get a more user-friendly output, given how common it is
(e.g. for `ToolchainRequirement`).

FSEntry: Throw an Exception when trying to read non-existent file ...

FSEntry.lookup can return null, and it would lead to a SEGV
with the attribute check, so add the forgotten check first.

PackageManager: Make lookup lazy again ...

We want to avoid loading the whole cache whenever lookup is called,
as most invocations of dub should result in a call to lookup,
since dependency resolution is much rarer than building with an
existing dub.selections.json.

Clear an unprinted deprecation during dub build ...

This deprecation is currently not printed by DMD,
but shows up if '-de' is used while compiling.
This solution is a workaround, as a proper fix
would mean not using the function in the first place,
but that requires a more in-depth rework.

Move the I/O part of Project.loadSelections to PackageManager ...

By doing so we can remove a sizeable amount of duplication as well
as the last `Dub.loadPackage` override. The resulting API is not
ideal, for example it doesn't allow to distinguish between parsing
errors and non-existent file, but will have to do for now.

Don't call `getPackageIterator` from `loadGitPackage` ...

`getPackageIterator` API forces us to do a refresh, which loads all
packages on the filesystem. However, for `loadGitPackage`'s use case,
we actually can simplify the check quite a bit.

Doing so means that we can now avoid doing a scan for projects
that use SCM-only dependencies.

Test Plan: On master, running the test (without the fix) triggers:
```
core.exception.AssertError@source/dub/test/base.d(790): Trying to access poisoned path: /dub/user/packages/poison/1.0.0/poison/dub.json
```
While with the fix, the test passes.

Clear up two deprecations triggering in unittest ...

Those are trivially fixed by using the new way of doing things.

Merge remote-tracking branch 'upstream/stable' ...

This brings in the OMF fix required for master's CI to be green.

Trivial: Remove some no-longer-needed imports ...

Now that we are properly mocking file removal in store,
those imports are not used as the function no longer
does IO directly.

Remove support for OMF, make MsCOFF be x86 ...

Now that OMF support is being removed, dmd-latest is broken in the CI.
Since DMD no longer supports it, and we are mostly concerned about
supporting the latest 10 releases, we're keeping x86_omf and x86_mscoff
available but making them aliases to x86.

Merge remote-tracking branch 'upstream/stable' into merge_stable

update version to v1.38.0

Fix regression in module-declarations parser

Merge remote-tracking branch 'upstream/stable' into merge_stable

update version to v1.38.0-rc.1

Move the code for collecting package information to a separate method.

Reorder code so that local functions come before the high-level algorithm.