extensionSystem: Fix extension reloading

Unloading an extension has become an async operation, but we aren't
awaiting the result. That means that we recreate the extension
object *before* we remove the "old" extension object from the map,
with the effect that the reloaded extension is removed completely.

https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/6507

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2694>

js/ui/extensionSystem.js

@@ -432,7 +432,7 @@ var ExtensionManager = class extends Signals.EventEmitter {
         let { uuid, dir, type } = oldExtension;
 
         // Then unload the old extension.
-        this.unloadExtension(oldExtension);
+        await this.unloadExtension(oldExtension);
 
         // Now, recreate the extension and load it.
         let newExtension;