Force last owner of a room to pass ownership when leaving (#5094)

* Move `ChangeRoles*` classes to their own module so they can be shared

* Hook the change roles screen to the leave room action, add confirmation dialogs

* Use enum instead of sealed interface for `ChangeRoomMemberRolesListType`

* Try to improve communications between nodes

* refactor (leave room) : makes sure to expose only necessary code from api module

* Add `:libraries:previewutils` module to share some test fixtures used for UI previews

* Update screenshots

---------

Co-authored-by: ElementBot <android@element.io>
Co-authored-by: ganfra <francoisg@matrix.org>

libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/room/PowerLevelRoomMemberComparator.kt

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2025 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.ui.room
+
+import io.element.android.libraries.matrix.api.room.RoomMember
+import java.text.Collator
+
+// Comparator used to sort room members by power level (descending) and then by name (ascending)
+class PowerLevelRoomMemberComparator : Comparator<RoomMember> {
+    // Used to simplify and compare unicode and ASCII chars (á == a)
+    private val collator = Collator.getInstance().apply {
+        decomposition = Collator.CANONICAL_DECOMPOSITION
+    }
+    override fun compare(o1: RoomMember, o2: RoomMember): Int {
+        return when {
+            o1.powerLevel > o2.powerLevel -> return -1
+            o1.powerLevel < o2.powerLevel -> return 1
+            else -> {
+                collator.compare(o1.sortingName(), o2.sortingName())
+            }
+        }
+    }
+}