windows: drive letters (borg2)

[ThomasWaldmann]

Check the test suite about windows drive letters - do we have enough tests?

As borg is a POSIX backup tool and we also want to be cross-platform (e.g. extract a windows backup on a linux machine), maybe the best way is to map C:\some\path to C/some/path and store that path into archived items.

There is already SOME code for this, but more testing, including practical tests is needed.

[trxvorr]

hey @ThomasWaldmann id like to work on this
could you assign it to me

[ThomasWaldmann]

@trxvorr this issue needs that PR #9264 gets merged first, do you want to review that?

[ThomasWaldmann]

The drive letter is case-insensitive on Windows, but guess we should normalize it so it is always uppercase in borg archives.