[Feature] Make vanilla buffs configurable

[qixils]

Increased structure generation, wither skeleton drops, etc might be nice to toggle off for a challenge (I know Markus community does the occasional "painful async" where all the settings are set very high)

[MrRedstone54]

This commit starts this process in regards to structure generation, but modifying the vanilla values needs to be datagened in some fashion. The defaults, upon greater inspection, have no rhyme or reason to them, and there should be a serious discussion on whether we set new modified values when we do implement configurable structure spawnrates.