[MM-7968] restrict creation of direct channels to team members (#17222)

* restrict creation of direct channels to team members

* run make i18n-extract

* add suggestions from hahmadia

* place common-team-check logic in app layer

* use flat SQL query

* show more specific error message to user

* MM-7968: Fmt file.

* MM-7968: Fix for moved session field.

Co-authored-by: Max Erenberg <max.erenberg@mattermost.com>
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>
Co-authored-by: Martin Kraft <martinkraft@gmail.com>
Co-authored-by: Martin Kraft <martin@upspin.org>

store/retrylayer/retrylayer.go

@@ -8762,6 +8762,26 @@ func (s *RetryLayerTeamStore) GetChannelUnreadsForTeam(teamID string, userID str
 
 }
 
+func (s *RetryLayerTeamStore) GetCommonTeamIDsForTwoUsers(userID string, otherUserID string) ([]string, error) {
+
+	tries := 0
+	for {
+		result, err := s.TeamStore.GetCommonTeamIDsForTwoUsers(userID, otherUserID)
+		if err == nil {
+			return result, nil
+		}
+		if !isRepeatableError(err) {
+			return result, err
+		}
+		tries++
+		if tries >= 3 {
+			err = errors.Wrap(err, "giving up after 3 consecutive repeatable transaction failures")
+			return result, err
+		}
+	}
+
+}
+
 func (s *RetryLayerTeamStore) GetMember(ctx context.Context, teamID string, userID string) (*model.TeamMember, error) {
 
 	tries := 0