device group (#10781)

1. Rename `Group` tab to `Accessible devices`
2. Add accessible device groups at the top of search list
3. option `preset-device-group-name` and command line `--assign --device_group_name`

Signed-off-by: 21pages <sunboeasy@gmail.com>

flutter/lib/mobile/pages/connection_page.dart

@@ -174,6 +174,7 @@ class _ConnectionPageState extends State<ConnectionPage> {
                           rdpPort: '',
                           rdpUsername: '',
                           loginName: '',
+                          device_group_name: '',
                         );
                         _autocompleteOpts = [emptyPeer];
                       } else {