Merge 3.6.2 into master (#5211)

* Add webhook cache

* Add channel by name cache

* Fxing profiles in channels cache

* Fix merge

api/command_join.go

@@ -34,7 +34,7 @@ func (me *JoinProvider) GetCommand(c *Context) *model.Command {
 }
 
 func (me *JoinProvider) DoCommand(c *Context, args *model.CommandArgs, message string) *model.CommandResponse {
-	if result := <-app.Srv.Store.Channel().GetByName(c.TeamId, message); result.Err != nil {
+	if result := <-app.Srv.Store.Channel().GetByName(c.TeamId, message, true); result.Err != nil {
 		return &model.CommandResponse{Text: c.T("api.command_join.list.app_error"), ResponseType: model.COMMAND_RESPONSE_TYPE_EPHEMERAL}
 	} else {
 		channel := result.Data.(*model.Channel)