This commit switches all of the manually allocated and freed arrays of
data in `multires_reshape_smooth` for various core container types,
depending on the specific usecase. As a direct result, many of the
parameters which were previously tagged as `const` are no longer.
Additionally, this allows for removing some manually tracked `size`
values.
Pull Request: https://projects.blender.org/blender/blender/pulls/140446
a6d3fa40ca