Add option in the Checkpoint entity to change the color used in its animation overlay

### I am planning on implementing this myself

No

### Describe your request

The Checkpoint entity looks for an appropriately named checkpoint decal in its room, and then gives it a blue-white animation overlay. This can clash visually with recolors of the checkpoint decal, so an option to change the tint used would be incredibly convenient. Currently, the entity just uses Color.White in Added, Update, and orig_turnOn to generate this tint; an option in the data of the entity to replace this with one of XNA's built-in colors (or an arbitrary hex code) would both fulfill the request and be amazing.

### Additional context

_No response_