What does this commit do??
This commit introduces two changes:
1. As a follow up review comment to
cc463c3e9b, we remove the top level
recipientNames cache in composer message to be a property of the
`ComposerMessage` component instead. Across components, we're more
likely to get a cache miss than a hit since we're caching the entire
recipient array so we can just drop it. If we really need this
optimisation, we should probably use a map and cache the information for
each user instead. However, the request is fairly cheap so we avoid that
optimisation for now.
2. This commit adds a debounce to `_typeReply` as well since we were not
debouncing and the method was being called each time we received the
event.
91588cf938