update version to v1.37.0

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

update version to v1.37.0-rc.1

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.

Trivial: Simplify ensureDirectory ...

mkdirRecurse will not do anything if the directory already exists,
so there is no need to call existsDirectory.

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

Let unittest use PackageManager.store ...

No need to mock, all filesystem functions have been mocked
by the PackageManager now.

VFS: Implement file attributes ...

To more accurately reflect the real filesystem,
we now support the access and modification times
for FSEntry.

update version to v1.37.0-beta.1

CLI: Simplify control flow by bundling two operations together

Test that `add-path` packages take priority ...

This was not currently tested explicitly, and is currently
the reason why we still have the scanning behavior in the
PackageManager.
In order to remove the scanning behavior and have the PM
lazily scan packages, we first must add test to ensure
there will be no further regression.

Test: Make NativePath import public ...

So that tests can use 'NativePath' and 'toNativeString'.

Add the ability to re-invoke Dub with the same vfs ...

This will prove handy when writting tests that require multiple
invocation of Dub, such as idempotence tests, or things like
add-path which currently don't propagate their change through
Dub as they are one shot commands.

Mock IO in writeLocalPackageList / writeOverrides ...

Mocking IO is required for writeLocalPackageList,
as we want to test the 'add-path' behavior.
While it is not a big concern for overrides, as they
are deprecated and we are unlikely to add new tests,
it is easy to do, and already done for reading them.

Remove the need to mock PackageManager.refresh() ...

We can finally test the full features of the base function,
as we are now mocking the IO, not the logic.

Remove direct IO from Location.scanLocalPackages ...

This is one more step towards removing our mocking of refresh_.

PackageManager: Mock readText, do not mock load ...

This allows us to test the behavior of the base class much better,
by overriding the last IO function, readText.

Move Package.findPackageFile to PackageManager, mock ...

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

Remove the need for intermediate `.zip` file in PackageSupplier ...

By using a different overload of `retryDownload`,
we return the data instead of writing to disk,
ensuring that we don't have a lingering file
in memory and reducing IO.

This follow the same approach for deprecations as previous
`PackageSupplier` deprecations: it's an inevitable, but
easily fixable, breaking change for classes that implement
`PackageSupplier`, but it's a proper deprecation for client
code, based on the assumption that all the classes implementing
`PackageSupplier` are in Dub.

Fix ubyte[] download overload by avoiding a cast ...

We were using the default template parameter, `char`,
and as the documentation for `get` states:
> If asking for char, content will be converted from
> the connection character set (specified in HTTP
> response headers or FTP connection properties,
> both ISO-8859-1 by default) to UTF-8.

However we are downloading a binary so converting
it to UTF-8 will fail. Especially if we intend
to cast it to `ubyte[]` afterwards.

Trivial: Print the Exception message in retryDownload ...

This makes the source of the issue more obvious when using
the verbose flag.

Test: Directly mock writeFile/existsFile from PackageManager ...

This allows us to reduce the number of functions we override,
as we would like to test writeSelections and refresh directly,
not the copy of them we have.

Introduce FSEntry.removeFile, FSEntry.removeDir, refactor FSEntry.writeFile ...

Add the ability to remove directories and files,
and refactor writeFile to make this kind of function
easier to write.

Allow tests to call customCachePaths ...

This is now possible, as refresh has been mostly implemented.

Tests: Remove FSEntry.this dependency on TestDub ...

The dependency should always be the other way around (TestDub depends on FSEntry),
and this is an easy win to move.

Make FSEntry const and scope correct ...

This way we can use it in functions that are using
const/scope, like loadConfig.
As a minor improvement, the two `lookup` overloads
were moved next to one another.

Test: Move writePackageFile to UFCS, better document ...

This is another step in separating FSEntry from TestDub.

Merge both TestDub constructors ...

Those constructors had different but non-overlapping functionalities.
In the event one wanted to set one of the parameters passed to Dub
constructor but also initialize the FS, one was out of luck.

Remove FileInfo.timeCreated ...

As it is not available on all platforms, we can't really rely
on it for code, and it is indeed not used anywhere.

Tests: FSEntry.writeFile write to wrong directory ...

This was a subtle bug hidden by the fact that 'parent' exists
in the class. It was causing problems when calling 'print',
but luckily didn't affect anything else.