Can we hide the algo used when turning on encryption

[manuroe]

From riot-web created by AmandineLP: element-hq/element-web#8829

at least on /app as 'Amandine turned on end-to-end encryption (algorithm m.megolm.v1.aes-sha2)' is ugly as hell

[jryans]

While chatting more with @ara4n, he would like to have some kind of handling of unknown algorithms at the same time as the propose hiding here. I think he came up with a decent approach:

• When the algorithm is the one we expect (m.megolm.v1.aes-sha2), hide the algorithm as in this existing PR: %(senderName)s turned on end-to-end encryption.
• For anything else, show the algorithm as unrecognised: %(senderName)s turned on end-to-end encryption (unrecognised algorithm %(algorithm)s).

[bmarty]

@jryans I think it could even warn a bit more if m.megolm.v1.aes-sha2 is already the current algo in a e2e room, like, say: "%(senderName)s is trying to change end-to-end encryption algorithm of the room to %(algorithm)s, which is forbidden". Not sure that it can happen (the sent event should probably be rejected by the homeserver?)