Change user permission by using a new apply button (#12346)

* Add PowerLevelSelector.tsx.
It's extracting the current behavior of the privileged users and muted of `RolesRoomSettingsTab.tsx` into a dedicated component.
It's also adding a new apply button.

* Use `PowerLevelSelector` to render privileged and muted users in `RolesRoomSettingsTab`

* Update existing tests

* Add playwright test

* Fix typo

* Fix typo

res/css/views/settings/_PowerLevelSelector.pcss

@@ -0,0 +1,21 @@
+/*
+ *
+ * Copyright 2024 The Matrix.org Foundation C.I.C.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * /
+ */
+
+.mx_PowerLevelSelector_Button {
+    align-self: flex-start;
+}