Added the ability to pull toys

I've added the ability to grasp adjacent toys and drag them with the monster. It's done with the button pad or right stick on the controller; or the arrow keys on the keyboard, at present. (I'm aware that the X button and Y button are swapped, that will be fixed in the next update). The game was initially designed to be more of a puzzle, like Sokoban; but it has more of an arcade top-down action vibe to it at this point and I'm leaning into that. Toys pushed against the wall should be recoverable.

There are also still a lot of simplified gray-box graphics in there, like a white circle for visual feedback on gripping. That's going to be something else later, but I prefer to show this stuff over tell it.

Let me know what y'all think!