Enable MySQL, PgSQL in CodeQL
#2760 (closed) enabled github's CodeQL checks. However, there were difficulties for MySQL, and Postgres (see this thread and the links in it). It seems hammer had some difficulties installing dependencies and then accessing the database.
Note: CodeQL is only available on github. This is the first pipeline we have for our mirror on github. This ticket may cover other generic changes.
The goal of this ticket is to figure out why exactly hammer had problems, fix them and enable both MySQL and Postgres.
We have a separate repo for experiments with github. This may come in handy.