Fix problem with firstname options and buffer view

[Wordluc]

Fix issue: #3157 (comment)

[jamestrew]

Hmm.. I think this is an issue that plagues various other places involving plenary's Path class and windows paths with mixed path separators.
This is probably best fixed upstream in plenary.

[Wordluc]

@jamestrew why the problem is plenary? the problem seems to be vim.fn.getbufinfo(bufnr)[1], that return the "wrong" result

[radlinskii]

This resolves the issue on my machine with Windows 11, together with path_display set to filename_first works very well

[jamestrew]

This messes up unix paths.
We could do a workaround but my preference is to fix this in plenary.

why the problem is plenary? the problem seems to be vim.fn.getbufinfo(bufnr)[1], that return the "wrong" result

I say this because we use plenary for all the cross-platform path stuff and the path from getbufinfo eventually gets fed into plenary.Path. If we fix the issue in plenary, we can fix this + like 3 other nearly identical issues.

I'll try to work on this week.