Support MSC3958: Suppress notifications from message edits

[andybalaam]

MSC3958 adds a new default push rule. It has now been merged into the spec and implemented in various servers e.g. Synapse.

matrix-js-sdk has a copy of the default push rules that it uses under certain circumstances. We should add this new push rule to the list of default rules.

[nikkuAg]

Is this issue still open? I would like to work on this

[andybalaam]

Yes, it is still open.