feat(parse): add _type-id_ production for type_of

[JohelEGP]

Updating some code didn't go as expected:

export expect: (x: type_of(boost::ut::eq(i64(), i64()))) _ = boost::ut::expect(x);
export expect: (x: std::type_identity_t<CPP2_TYPEOF(boost::ut::eq(std::vector<int>(), std::vector<int>()))>) _ =
  boost::ut::expect(x);

This PR remedies that.