Doing so takes down two birds with one stone.
1. `ResumeOverlay` having to manually apply cursor scale to its "resume
cursor".
2. Resume cursor input handling scaling up with the gameplay setting. Now, only the sprite itself gets scaled.
Turns out that `CreateInputManager` is called more than once, and some
mods (ie. `InputBlockingMod`) rely on consuming the "main" one. So let's
go back to accessing and exposing in `DrawableOsuRuleset` rather than
storing out own reference.