Saves having this defined in 20+ places. If we ever make any changes to
shear, it's 100% going to need to be applied to every usage (there will
never be a case of multiple different shears in the game).
Also fixes a mismatching definition in `ShearedNub`.
This is important when using dynamic compiling to rapidly iterate. Until we actually split projects out into pieces (like the abstract ruleset project we have talked about) there is no advantage to using internal in the osu! game code.