Pass a wrapped VFS down into `clang::createInvocationFromCommandLine` so
that the working directory is set and then used in the underlying Clang
`CompilerInstance`.
Fixes the possibility of differing modules hashes when the same
arguments are used in Clang directly vs from the importer.
Resolves rdar://79376364
The VFS tests were using Unix absolute paths, which does not play well
when Windows see them as relative to the current drive letter.
By using the temporal directory, both Windows and Unix can use the same
paths and avoid the problem.
Additionally, a couple of inputs have to be transformed into the native
path format, because sourcekitd-test compares the inputs as strings, and
they need to match exactly. So the source file and the name of the VFS
entries are transformed into native using the helper from LLVM support.
Propagates the VFS to the SemanticInfo that gets used when then
original editor.open is syntactic only.
Removes unnecessary filesystem arg (get filesystem from class field
instead).
Adds test for the VFS being propagated into the SemanticInfo.
Refactors test/SourceKit/CursorInfo/injected_vfs.swift to use
-print-raw-response for all its tests, for consistency.
