This simplifies `PathWithPosition` by making the common use case
concrete and removing the manual, incomplete Windows path parsing.
Windows paths also don't get '/'s replaced by '\\'s anymore to limit the
responsibility of the code to just parsing out the suffix and creating
`PathBuf` from the rest. `Path::file_name()` is now used to extract the
filename and potential suffix instead of manual parsing from the full
input. This way e.g. Windows paths that begin with a drive letter are
handled correctly without platform-specific hacks.
Release Notes:
- N/A
Still TODO:
* [x] hide this UI unless you have some ssh projects in settings
* [x] add the "open folder" flow with the new open picker
* [ ] integrate with recent projects / workspace restoration
Release Notes:
- N/A
