[llvm] [llvm-debuginfo-analyzer] Remove `LVScope::Children` container (PR #144750)

[Javier Lopez-Gomez via llvm-commits]

jalopezg-git wrote:

> The changes that introduce the `none : unsorted output` should be in a separated patch, as it is a general feature, independent of the `children` removal and associated with `LVObject::ID`.

I removed the change from this PR.  Actually, I am not totally convinced that we should have it, given that we also have `--output-sort=offset`, which should yield the same result?

If any, `--output-sort=none` should perform a bit better if we avoid calling `LVScope::sort()` at all.  As it is totally independent, let's discuss that after this gets in.

https://github.com/llvm/llvm-project/pull/144750