IP address support

Objects from the python `ipaddress` module should map to Postgres `inet` types.

Note that the python shared `ipaddress._Base_Address` class is private/undocumented

The issue names Python's ipaddress module and PostgreSQL inet types but no files, tests, or entry points. Locate the library's Python-to-PostgreSQL type mapping and inspect how address objects are identified, keeping the private _Base_Address warning in mind. Done means supported ipaddress objects map to inet types with coverage for the relevant address forms.

Written by the indexing model from the issue text.