Grammar/tree commit only, no logic. Will populate release note
in commit implementing logic.

Release note: None

Release note (sql change): Added support for ALTER DEFAULT PRIVILEGES
and default privileges stored on databases.

All objects created in a database will have the privilege set defined
by the default privileges for that type of object on the database.
The types of objects are TABLES, SEQUENCES, SCHEMAS, TYPES.

Example: ALTER DEFAULT PRIVILEGES GRANT SELECT ON TABLES TO foo
makes it such that all tables created by the user that executed the
ALTER DEFAULT PRIVILEGES command will have SELECT privilege on the table
for user foo.

Additionally, one can specify a role.
Example: ALTER DEFAULT PRIVILEGES FOR ROLE bar GRANT SELECT ON TABLES TO foo.
All tables created by bar will have SELECT privilege for foo.
If a role is not specified, it uses the current user.

See: https://www.postgresql.org/docs/current/sql-alterdefaultprivileges.html

Currently, default privileges are not supported on the schema.
Specifying a schema like ALTER DEFAULT PRIVILEGES IN SCHEMA s will error.

WITH GRANT OPTION is ignored.
GRANT OPTION FOR is also ignored.

Minor fixes from Arul's PR feedback.
Remove GRANT ALL for types for creator of type.

Release note: None

Release note: None

Release note: None

Release note: None