treewide(refactor): rename files to follow the same style

lib/controllers/top_level_spaces.dart

@@ -0,0 +1,14 @@
+import "package:fast_immutable_collections/fast_immutable_collections.dart";
+import "package:flutter_riverpod/flutter_riverpod.dart";
+
+class TopLevelSpacesController extends Notifier<IList<String>> {
+  @override
+  IList<String> build() => .new();
+
+  void set(IList<String> newSpaces) => state = newSpaces;
+
+  static final provider =
+      NotifierProvider<TopLevelSpacesController, IList<String>>(
+        TopLevelSpacesController.new,
+      );
+}