Fixes a bug and adds a feature for shared channels:
- The Bug: when creating new shared channels, users that had already been sync'd via another channel were not added to the new channel's member list, since the users were not sync'd again. This PR sync's users per channel.
- The Feature: support custom statuses
Support for handling username collisions between remote clusters. Users belonging to remote clusters have their username changed to include the remote name e.g. wiggin becomes wiggin:mattermost.
@mentions are also modified so the munged username is replaced with the original username when the post is sync'd with the remote the user belongs to.
When adding remote users:
- append the remote name to the username with colon separator
- append the remote name to the email address with colon separator
- store the original username and email address in user props
- when resolving @mentions replace with the stored original username
Remote Cluster Service
- provides ability for multiple Mattermost cluster instances to create a trusted connection with each other and exchange messages
- trusted connections are managed via slash commands (for now)
- facilitates features requiring inter-cluster communication, such as Shared Channels
Shared Channels Service
- provides ability to shared channels between one or more Mattermost cluster instances (using trusted connection)
- sharing/unsharing of channels is managed via slash commands (for now)
