Review and fix issues with find

okay, problems that I see:

- [ ] `maxdepth` is not supported
- [ ] `withdirs` is not supported (must have for expand path)
- [ ] doesn't check bucket name `find('.')` and `find('etasderwer')` return the same result
- [ ] it keeps appending ids to cache every time even for already known
- [ ] cache is not locked (multithreading support) - this is a bit more advanced and less critical to start with

_Originally posted by @shcheklein in https://github.com/iterative/PyDrive2/issues/229#issuecomment-1242791704_

Start at the find entry point and trace how maxdepth, withdirs, bucket validation, and cache updates are handled. Check each listed behavior, including duplicate IDs and cache locking, and consider the issue done only when the supported cases work without regressing the existing find behavior.

Scritto dal modello di indicizzazione a partire dal testo della issue.