Updated room sorting

Change the LastActivity sort order to Activity and update to a more flexible way of sorting based on an order from model roles.
Add options to actually switch between Alphabetical and Activity

Based on some old work by @tdfischer 

implements #103

src/qml/GeneralSettingsPage.qml

@@ -65,6 +65,29 @@ FormCard.FormCardPage {
             }
         }
     }
+    FormCard.FormHeader {
+        title: i18n("Room list sort order")
+    }
+    FormCard.FormCard {
+        FormCard.FormRadioDelegate {
+            text: i18nc("As in 'sort something based on last activity'", "Activity")
+            checked: Config.sortOrder === 1
+            enabled: !Config.isSortOrderImmutable
+            onToggled: {
+                Config.sortOrder = 1
+                Config.save()
+            }
+        }
+        FormCard.FormRadioDelegate {
+            text: i18nc("As in 'sort something alphabetically'", "Alphabetical")
+            checked: Config.sortOrder === 0
+            enabled: !Config.isSortOrderImmutable
+            onToggled: {
+                Config.sortOrder = 0
+                Config.save()
+            }
+        }
+    }
     FormCard.FormHeader {
         title: i18n("Timeline Events")
     }

src/qml/RoomListPage.qml

@@ -148,7 +148,6 @@ Kirigami.Page {
                     property bool filterTextJustChanged: false
 
                     sourceModel: root.roomTreeModel
-                    roomSortOrder: SortFilterRoomTreeModel.Categories
                     activeSpaceId: spaceDrawer.selectedSpaceId
                     mode: spaceDrawer.showDirectChats ? SortFilterRoomTreeModel.DirectChats : SortFilterRoomTreeModel.Rooms
                 }