This reverts commit 53d94b8091b36847bb9e495c76bb5a3ec2a2fdb5.

The reason for the revert is that the commit in question introduced a
regression where certain modules, functions and classes that were
exposed before were no longer exposed.

See https://github.com/gitpython-developers/GitPython/pull/1352#issuecomment-932757204
for additional information.

All `from <module> import *` has now been replaced by
`from <module> import X, Y, ...`.

Contributes to #1349

delete_head and Head.delete historically accept either Head objects
or a str name of a head.  Adjust the typing to match.  This
unfortunately requires suppressing type warnings in the signature of
RemoteReference.delete, since it inherits from Head but does not
accept str (since it needs access to the richer data of
RemoteReference).

Using assignment to make add an alias for create unfortunately
confuses mypy, since it loses track of the fact that it's a
classmethod and starts treating it like a staticmethod.  Replace
with a stub wrapper instead.