file_browser automatically set initial_path when given value

[yairchu]

Description

Now that file_browser supports default file selection (#7468),
when that feature is used, the browser may start at a different path than the one where the selection is, which may seem surprising.

Suggestion: when no initial_path is given, set it to the parent folder for the default selection.

If the default selection contains several files in different folders (is that supported?), default the initial_path to the common ancestor.

Are you willing to submit a PR? (You must receive approval from the team before submitting a PR.)

• Yes

Alternatives

No response

Additional context

No response

[kirangadhave]

Thanks @yairchu for filing the issue. We appreciate you willing to submit a PR.