doc: Generate develop/api/overview.rst API table from doxygen

A new extension, api_overview.py, is used to, leveraging doxygen's
Python module doxmlparser, parse the doxygen generated XML files.
All groups ('defgroup' and 'addtogroup' tags) are collected, alongside
their 'version' and 'since' info.

From there, a new Sphinx directive `api-overview-table` is populated,
including the name of the group, and if available, their 'since' and
'version' information.

Signed-off-by: Ederson de Souza <ederson.desouza@intel.com>
Signed-off-by: Anas Nashif <anas.nashif@intel.com>