Self-hosted roles: supabase_admin and postgres (and local dev supabase cli...), non-public schema

CREATE SCHEMA IF NOT EXISTS myschema;

-- Allow API access
GRANT USAGE ON SCHEMA myschema TO anon, authenticated, service_role;
GRANT ALL ON ALL TABLES IN SCHEMA myschema TO anon, authenticated, service_role;
GRANT ALL ON ALL ROUTINES IN SCHEMA myschema TO anon, authenticated, service_role;
GRANT ALL ON ALL SEQUENCES IN SCHEMA myschema TO anon, authenticated, service_role;
ALTER DEFAULT PRIVILEGES FOR ROLE postgres IN SCHEMA myschema GRANT ALL ON TABLES TO anon, authenticated, service_role;
ALTER DEFAULT PRIVILEGES FOR ROLE postgres IN SCHEMA myschema GRANT ALL ON ROUTINES TO anon, authenticated, service_role;
ALTER DEFAULT PRIVILEGES FOR ROLE postgres IN SCHEMA myschema GRANT ALL ON SEQUENCES TO anon, authenticated, service_role;