Strip optional/default type-level attributes on .required()

[ssalbdivad]

This would fix the following case:

// https://github.com/arktypeio/arktype/issues/1156
it("with default", () => {
  const t = type({ foo: "string = 'bar'" }).required();

  const expected = type({
    foo: "string",
  });

  // currently the types do not match because the default is not removed
  attest<typeof expected.t, typeof t.t>();

  attest(t.expression).equals(expected.expression);
});

Should also add cases for optionality on the value