The powers conferred by this chapter shall be in addition and supplemental to the powers conferred by any other law, and are not in substitution for such powers, and the limitations imposed by this chapter shall not affect such powers. The powers granted in this chapter may be exercised without regard to requirements, restrictions or procedural provisions contained in any other law or charter, except as expressly provided in this chapter. Any metropolitan government or any home rule municipality authorized under this chapter to create a metropolitan hospital authority may do so without the necessity of a charter amendment, notwithstanding anything in its charter to the contrary.