* FIX: Channel archive N1 when serializing current user
The `ChatChannelSerializer` serializes the archive for the
channel if it is present, however this was causing an N1 for
the current user serializer in the case of DM channels, which
were not doing `includes(:chat_channel_archive)` in the
`ChatChannelFetcher`.
DM channels cannot be archived, so we can just never try to serialize
the archive for DM channels in `ChatChannelSerializer`, which
removes the N1.
* DEV: Add N1 performance spec for latest.html preloading
We modify current user serializer in chat, so it's a good
idea to have some N1 performance specs to avoid regressions
here.
5f4911dae8