Improve handling of Contact groups

Is your feature request related to a problem? Please describe.

Actually the handling of contact groups is really confusing for new users.

1. If you create a new group and click on the menu "contacts" (Contacts are reloading) the group doesn't exists. This is really confusing new nextcloud users.
2. Actually it seems not to be possbile to move more than one contact to another group. Example: I want to delete a group and needs to move every single contact to another group. After this I need to reload the page and the group is removed.

Describe the solution you'd like

1. When a user creates a new group it should be saved immediately. It shouldn't matter if the group contains contacts or not. Additionally the user must have the option "Delete" to delete the group. If a user deletes a group that contains contacts a dialog should be display where the contacts should be moved before deleting.
2. Batch operation for moving contacts to other groups should be supported (maybe for other operations like delete of a contacts too).

Describe alternatives you've considered

No response

Additional context

No response

The issue does not name files or tests, so first locate the contact-group creation, deletion, and contact-selection flows in the JavaScript app. Define the behavior for saving empty groups, deleting groups with contacts, and moving multiple contacts, then verify each flow in the UI, including the requested confirmation dialog and reload behavior.