trigger hooks when adding or removing user into group

[grosmanal]

The problem

The post_app_addaccess and post_app_removeaccess are not triggered when adding or removing a user to / from a group with the commands yunohost user group add and yunohost user group remove

Solution

Add a hook_callback call in the appropriate function.

PR Status

To be tested

How to test

• install a app with post_app_addaccess and post_app_removeaccess hooks
• add a user into a group
• => post_app_addaccess hook is called
• remove a user from a group
• => post_app_removeaccess hook is called

This PR is related to YunoHost/issues#2213

[Tagadda]

Looks good!

[kay0u]

LGTM, I think we can wait bookworm to merge this PR?