Rename feature to enable-atomic-polyfill

Having a feature named the same as a dependency when you also need to
enable dependency features leads to wonky results

Cargo.toml

@@ -22,7 +22,7 @@ maintenance = { status = "actively-developed" }
 default = ["std", "atomic"]
 std = []
 atomic = ["spin"]
-atomic-polyfill = ["once_cell/atomic-polyfill", "dep:atomic-polyfill"]
+enable-atomic-polyfill = ["atomic-polyfill", "once_cell/atomic-polyfill"]
 # Enables derive(Bundle)
 macros = ["hecs-macros", "once_cell"]
 # Enables the serialize::column module