Github-based Rule Editing

[gerrycampion]

Parent issue for decommissioning Rule Editor and replacing it with a github-based approach

[eljanssens]

@gerrycampion and @SFJohnson24: one thing that we need to take into account is keeping a training environment where people can practice rule writing. This is important as well for the official CDISC Open Rules HOIT. For me it doesn't matter where, as long as it is very accessible for learners. Should we add another sub-ticket to not forget this?