Update MSC3912 implementation: Redaction of related events

[giomfo]

Description:

Since MSC3912 has been implemented by #7988, we introduced 2 changes into the MSC for which we need to update this implementation :

• the new property with_relations has been renamed with_rel_types (to prevent us from introducing a new term ("relations") to refer to event relationships). Only the stable name is changed, we keep the existing unstable one.
• we introduced a catch-all "*" value, which if found in the list means "any relation type"

We should apply changes in the SDK only for the first point. The SDK seems already support the second point.
This second point should be taken into account mainly in a moderation tool where the client may not be aware of the relation types associated with an event. I'm not sure there is already a use case at the application level

Are you willing to provide a PR?

Yes