Cache virtual/native room mappings when they're created
Cache virtual/native room mappings when they're created

Otherwise we look up the mapping immediately afterwards and the
remote echo of the account data hasn't come back yet, so we get
nothing.

Fixes "You're already in a call with this person" bug with virtual
rooms.

matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk