AssetPath doesn't implement `parent`

[mhsmith]

It implements the documented Traversable interface, but it doesn't implement the undocumented SimplePath interface used by importlib.metadata. This causes an exception from this code in numpy/testing/_private/utils.py:

np_dist = importlib.metadata.distribution('numpy')
....
np_dist.locate_file('numpy')

  File "/data/data/com.chaquo.python.pkgtest3/files/chaquopy/AssetFinder/requirements/numpy/testing/_private/utils.py", line 86, in <module>
  File "stdlib/importlib/metadata/__init__.py", line 922, in locate_file
AttributeError: 'AssetPath' object has no attribute 'parent'

Review all Path properties and methods to see if there's anything else we should add at the same time.

[mhsmith]

The following workaround is good enough for numpy. In the production fix, we should also make it possible to traverse out of the importer root and get a normal Path object.

@property
def parent(self):
    return type(self)(str(self).rpartition("/")[0])

from java.android import importer
importer.AssetPath.parent = parent