Notwithstanding the provisions of the general statutes or any special act, charter, special act charter, home rule ordinance or local law, two or more municipalities may jointly perform any function that each municipality may perform separately under any provisions of the general statutes or of any special act, charter or home rule ordinance by entering into an interlocal agreement pursuant to sections 7-339a to 7-339l, inclusive. As used in this section, “municipality” means any municipality, as defined in § 7-187, any district, as defined in § 7-324, any metropolitan district or any municipal district created under § 7-330 and located within the state of Connecticut.