Zoom: Move enabling zoom to a new player object property

Default enabled for no change in default behaviour.
Remove 'zoom' privilege.

builtin/game/privileges.lua

@@ -82,10 +82,6 @@ core.register_privilege("rollback", {
 	description = "Can use the rollback functionality",
 	give_to_singleplayer = false,
 })
-core.register_privilege("zoom", {
-	description = "Can zoom the camera",
-	give_to_singleplayer = false,
-})
 core.register_privilege("debug", {
 	description = "Allows enabling various debug options that may affect gameplay",
 	give_to_singleplayer = false,