added Files Locking support

[bigcat88]

Implemented using WebDAV requests.

    async def lock(self, path: FsNode | str, lock_type: LockType = LockType.MANUAL_LOCK) -> None:
        """Locks the file.

        .. note:: Exception codes: 423 - existing lock present.
        """
        pass
        
    async def unlock(self, path: FsNode | str) -> None:
        """Unlocks the file.

        .. note:: Exception codes: 412 - the file is not locked, 423 - the lock is owned by another user.
        """ 
        pass   

Reference: https://github.com/nextcloud/files_lock

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (10417cf) 99.83% compared to head (df9fa6a) 99.84%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #227   +/-   ##
=======================================
  Coverage   99.83%   99.84%           
=======================================
  Files          42       42           
  Lines        4943     5010   +67     
=======================================
+ Hits         4935     5002   +67     
  Misses          8        8           

Files	Coverage Δ
nc_py_api/__init__.py	100.00% <100.00%> (ø)
nc_py_api/_version.py	100.00% <100.00%> (ø)
nc_py_api/files/__init__.py	99.65% <100.00%> (+0.05%)	⬆️
nc_py_api/files/_files.py	98.52% <100.00%> (+0.06%)	⬆️
nc_py_api/files/files.py	100.00% <100.00%> (ø)