Add filter for human users on manage group/project members UI

Proposal

Currently, it is possible to add ?user_type=human at the end of a manage group/project members URL, resulting in any bot users created as part of a group/project access token or a service account not being included in the UI.

There should be a dropdown option when filtering by user type to select human. Currently, only service account is available as an option

Current dropdown behaviour:

Default view:

View when adding ?user_type=human manually to the URL: