[Feature] Clumping mode

[meza]

I'd love a way to smooth out the selections to avoid single chunk deletions within a patch of non-selected chunks.
In essence MCA selector does what we ask it to do but with new structures and biomes coming to MC lately paired with their not-so-smart generation rules we do end up with weird worlds when a single chunk gets deleted in a patch of non-deleted chunks.

I'd love to be able to tell MCA selector to only consider patches below/above a certain size to be marked.
A patch would maybe consist of chunks with more than 1 neighbours also selected.

I feel like the radius setting could get us most of the way too but we definitely need the negative values there as in #448