Restore namespace parameter to actions!

This does not yet fix `derive(Action)`, but will conflict with a lot so
wanted to merge quickly.

crates/language_selector2/src/language_selector.rs

@@ -16,7 +16,7 @@ use ui::{prelude::*, HighlightedLabel, ListItem};
 use util::ResultExt;
 use workspace::{ModalView, Workspace};
 
-actions!(Toggle);
+actions!(language_selector, [Toggle]);
 
 pub fn init(cx: &mut AppContext) {
     cx.observe_new_views(LanguageSelector::register).detach();