[Consistency Review] There's no Array::stable_sort

[hackwaly]

Current behaviors

There's FixedArray::stable_sort, but not Array::stable_sort

FixedArray::stable_sort_by and Array::stable_sort_by is also missing.

Expected behaviors

There should be Array::stable_sort

Justification

[hackwaly]

It seems unstable version not always significantly faster than stable version.

I think we should expose only one sort func sticky on stable version instead of two sort and stable_sort.

If unstable version is much faster, we could provide another fast_sort func.