Notwithstanding any contrary provision of general or special law, no locality, or any agency thereof, including school boards, or any local housing or redevelopment authority created pursuant to § 36-4, that receives any funds from the Commonwealth, shall condition employment or any feature of employment, including promotion, on the basis of residency in a particular locality. This section shall not apply to (i) appointees of elected groups or individuals, (ii) officials and employees who by charter or other law serve at the will or pleasure of an appointing authority, (iii) deputies and executive assistants to the chief administrative officer of a locality, or (iv) agency heads, department heads or their equivalents or chief executive officers of government operations.