This adds support to the current sculpt sample detail operator to sample
a voxel size for the voxel remesher when sculpting on regular meshes.
It provides an approximation of a voxel size that is going to preserve
the sampled sculpt details after remeshing. It is not going to be 100%
accurate in all cases as it relies on having consistent edge length in
the whole sculpt, but it saves a lot of time and avoids guessing the
voxel size by trying different values.