Query::for_each_combinations(_mut)

## What problem does this solve or what need does it fill?
`Query::for_each_combinations(_mut)`, the `for_each` equivalent of `iter_combinations(_mut)`.

## What solution would you like?
The bug that is cited in the docs for `Query::iter_combinations` (https://github.com/rust-lang/rust/issues/62529), has been resolved. Another attempt at implementing it should be taken.

## What alternative(s) have you considered?
Don't implement it. Remove the comment about the bug.