Create a backend function to INSERT/DELETE users in usergroup

[robertandremitchell]

Description:

The usergroup to users conjunction table is necessary to manage the users.id that are part of a particular user group.

The easiest way to do this will be to query the users table for all ids/names to display in the drawer with a boolean to indicate if they are part of a usergroup.

If they are checked, that user_id/usergroup_id combination should have a row inserted into the usergroup_to_users table.

If they are unchecked, that user_id/usergroup_id combination should have a row deleted from usergroup_to_users table, if it exists.

This should be done via a Save Changes buttn, to avoid doing multiple insert/delete states.

Acceptance Criteria:

[linear]

QUE-174 Create a backend function to INSERT/DELETE users in usergroup