Game: isDebugDrawingColliders() and toggleDebugDrawColliders() #369

`Game.debugDrawColliders(enabled)` can turn collider drawing on and off, but there's no way to read the current state, so anything toggling it from a button has to keep its own flag (fighter example does this with `showColliders`).

Add, next to `debugDrawColliders()`:

• `isDebugDrawingColliders() as boolean`
• `toggleDebugDrawColliders() as boolean` - flips it, returns the new state

Names follow the existing `debugDraw*` setters. Probably worth adding the same getter for `debugDrawOcclusion`, `debugDrawSafeZones` and `debugDrawEntityDetails` while we're in there.