cleanup: Use type-safe comparisons

We have been using type-safe comparisons in new code for quite a while
now, however old code has only been adapted slowly.

Change all the remaining bits to get rid of another legacy style
difference.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2866>

js/ui/unlockDialog.js

@@ -778,7 +778,7 @@ export const UnlockDialog = GObject.registerClass({
 
     _onReset(authPrompt, beginRequest) {
         let userName;
-        if (beginRequest == AuthPrompt.BeginRequestType.PROVIDE_USERNAME) {
+        if (beginRequest === AuthPrompt.BeginRequestType.PROVIDE_USERNAME) {
             this._authPrompt.setUser(this._user);
             userName = this._userName;
         } else {