Move PyConf from Moore to LHCb

Why

As detailed in Moore#116 (closed), PyConf would be useful in numerous projects and not only Moore, so it is moved to LHCb.

How

PyConf is copied from Moore/master (Moore@ea9cbe37) using git-filter-repo and git rebase --rebase-merges as detailed here. With this procedure

1. the full git history of PyConf is preserved (in the simplest possible way, i.e. including merges)
2. the commit messages are rewritten (see screenshot below) to a. append a link to the original Moore commit (Moore@123456789) b. replace references to issues and MRs such as #12345 with Moore#12345

Some small tweaks were necessary after the automatic move

• Use only Gaudi algorithms in PyConf tests.
• Add python linting for PyConf to CI.
• Move PyConf rst documentation from Moore into module docstrings here. The documentation is still only built and deployed by the Moore CI.

Goes together with Moore!718 (merged)

Closes Moore#116 (closed)

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Here is an example of how a moved commit looks like on GitLab: