Replace the local_replace.py script

[ezio-melotti]

The local_replace.py extension has been used to automatically convert parts of messages posted to b.p.o into links, including: issues, messages, reference numbers, PEPs, files, tracebacks, etc. (see the triaging page of the devguide). Some of these links are already automatically handled by GitHub.

If we want to create links for the rest, a new tool should be written.

This tool will be used for new messages, but it might also be used either at import time, or after the issues have been imported to GitHub.

[ezio-melotti]

Autolinks could be used for some of these (e.g. PEP-XXX), but they aren't flexible enough to handle all cases.

A GitHub action should provide more flexibility -- autolinks could be still used in the meanwhile.