Fix `ProtoCommands::remove` inserting instead of removing

[Gino Valente]

The ProtoCommands::remove method is using the wrong command:

bevy_proto/bevy_proto_backend/src/proto/commands.rs

Lines 60 to 62 in 37a72d7

 pub fn remove<I: Into<T::Id>>(&mut self, id: I) { 
     self.add(ProtoInsertCommand::<T, C>::new(id.into(), None)); 
 }