Clean up checks and logics that are unnecessary due to MILC updates.
Use pathlib instead of os.path for readability.
Use the 'pytest' keyboard for the tests.
Add community layout for 'handwired/onekey/pytest' so we can test
community layouts.
The command now return all keymaps that's buildable for a
keyboard/revision. If the base directory of a keyboard does not contain
a 'rules.mk' file, nothing is returned. If the base directory contains a
'keymaps' directory, those keycaps will be returned for every revision.
`list_keyboards` replicates the `make list-keyboards` by globbing for all paths
that include `rules.mk` and then removing the paths that include `keymaps`.
This basis of this cli command could be reused in the future as a util, but is
not done so here since this would be the only place that would use it currently
Resolves#6911