MM-33903 rename slash commands & permission (#17494)

- rename slash commands
    - "remote" -> "secure-connection"
    - "share" -> "share-channel"
- change status icons to text (translated)
- remove channel invite "Description" field
- rename permission "manage_remote_clusters" -> "manage_secure_connections"

services/remotecluster/service.go

@@ -75,7 +75,7 @@ type TopicListener func(msg model.RemoteClusterMsg, rc *model.RemoteCluster, res
 // ConnectionStateListener is used to listen to remote cluster connection state changes.
 type ConnectionStateListener func(rc *model.RemoteCluster, online bool)
 
-// Service provides inter-cluster communication via topic based messages.
+// Service provides inter-cluster communication via topic based messages. In product these are called "Secured Connections".
 type Service struct {
 	server     ServerIface
 	httpClient *http.Client
@@ -90,7 +90,7 @@ type Service struct {
 	done                     chan struct{}
 }
 
-// NewRemoteClusterService creates a RemoteClusterService instance.
+// NewRemoteClusterService creates a RemoteClusterService instance. In product this is called a "Secured Connection".
 func NewRemoteClusterService(server ServerIface) (*Service, error) {
 	transport := &http.Transport{
 		Proxy: http.ProxyFromEnvironment,