Jump to bottom and mark messages read with Escape

Pressing the Escape key again when you're already at the bottom and
there are no unread messages takes you back to the room list like
before.

src/qml/Page/RoomPage.qml

@@ -77,7 +77,14 @@ Kirigami.ScrollablePage {
 
     Shortcut {
         sequence: StandardKey.Cancel
-        onActivated: applicationWindow().pageStack.get(0).forceActiveFocus()
+        onActivated: {
+            if (!messageListView.atYEnd || currentRoom.hasUnreadMessages) {
+                goToLastMessage();
+                currentRoom.markAllMessagesAsRead();
+            } else {
+                applicationWindow().pageStack.get(0).forceActiveFocus();
+            }
+        }
         enabled: !page.disableCancelShortcut
     }