Remove a member from a team

Creates or replaces the team's grant on the project; its members get it live, beside their own grants (each Postgres role at the level of the grant naming it). `admin` holds every role (the names in `pg_roles` are checked, then dropped). The grant is checked on every member's union of sources narrowed by their overrides, on every database of the project, as `putProjectGrant` checks one grant; a refusal names the member, the team and the database. Personal logins that stop qualifying are revoked, and every branch of the project reconciles its member roles. An unchanged grant writes nothing.