Automatically create mount directory with generated directory name

[teohhanhui]

Is your feature request related to a problem? Please describe.
I'd like to be able to mount multiple different encrypted directories without having to keep empty mount directories around.

Describe the solution you'd like
Select a parent directory where mount directories would be automatically created with (partially random?) generated directory names.

Additional context
e.g. I choose the parent directory /run/media/teohhanhui, and Vaults would generate /run/media/teohhanhui/Vaults-{uuid}

[teohhanhui]

An idea inspired by https://stackoverflow.com/a/15395191/1529493:

Generate the uuidv5 for the Vaults namespace:

teohhanhui@envy-x360:~> uuidgen --sha1 --namespace '00000000-0000-0000-0000-000000000000' --name io.github.mpobaschnig.Vaults
63602166-834c-5bac-bb94-e66c51adb6ec

Generate the uuidv5 for the encrypted directory's path:

teohhanhui@envy-x360:~> uuidgen --sha1 --namespace '63602166-834c-5bac-bb94-e66c51adb6ec' --name '/run/media/teohhanhui/Transcend TS2TSJ25H3B/Backups/2FA recovery codes'
e29c7abe-420d-572d-b17a-d880eb750d8d

[mpobaschnig]

This would be a good condidate as part of #54.