Generalize the description of the ACLs
Now that we can have project-less API token, having ACLs that say `in
this project` is confusing.
This commits generalize the descriptions of the ACLs and add an alembic
migration script that updates existing records.
Fixes https://pagure.io/pagure/issue/2441
Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>