Preemption.The provisions of any ordinance or resolution adopted before, on, or after the effective date of this amendatory Act of the 94th General Assembly by any unit of local government that impose restrictions or limitations on the picketing of an employer in a manner inconsistent with this Act are invalid, and existing ordinances and resolutions, as they apply to picketing, are void. It is declared to be the policy of this State that the regulation of picketing is an exclusive power and function of the State. A home rule unit may not regulate picketing. This Section is a denial and limitation of home rule powers and functions under subsection (h) of Section 6 of Article VII of the Illinois Constitution.