[FIX] mail: improved message_fetch for moderated channels

There was two issues with the previous code:

	1. It was using a weak heuristic to determine whether the
	   current thread is a channel (ID is a number)
	2. For any channel, it was always passing `moderated_channel_ids`
	   with some values to the server, even though the channel
	   is not moderated at all.

This commit solves both issues by passing `moderated_channel_ids`
only for moderated channel. Also, this logic has been moved from
SearchableThread to Channel, since moderation makes only sense for
channels and channels are aware of whether they are moderated or
not.

0 files changed, 0 insertions, 0 deletions