* Adds logical deletes to shared channel remotes and remote clusters
Instead of physically deleting the shared channel remote and remote
clusters records when a channel is unshared, a remote uninvited or a
remote cluster is deleted, now those have a logical `DeleteAt` field
that is set.
This allows us to safely restore shared channels between two remote
clusters (as of now resetting the cursor without backfilling their
contents) and to know which connections were established in the past
and now are severed.
* Delete the index in remoteclusters before adding the new column
* Fix bad error check
* Adds Shared Channel management API endpoints
New endpoints for the following routes are added:
- Get Shared Channel Remotes by Remote Cluster at `GET
/api/v4/remotecluster/{remote_id}/sharedchannelremotes`
- Invite Remote Cluster to Channel at `POST
/api/v4/remotecluster/{remote_id}/channels/invite`
- Uninvite Remote Cluster to Channel at `POST
/api/v4/remotecluster/{remote_id}/channels/uninvite`
These endpoints are planned to be used from the system console, and
gated through the `manage_secure_connections` permission.
* Adds i18n messages for API errors
* Fix pagination flaky test
* Fix linter
* Adds the posibility of filtering shared channel remotes by home
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Co-authored-by: Mattermost Build <build@mattermost.com>
