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/extensionSystem.js

@@ -402,7 +402,7 @@ export class ExtensionManager extends Signals.EventEmitter {
                 throw new Error(`property "${prop}" is not of type ${typeName}`);
         }
 
-        if (uuid != meta.uuid)
+        if (uuid !== meta.uuid)
             throw new Error(`uuid "${meta.uuid}" from metadata.json does not match directory name "${uuid}"`);
 
         let extension = {