Auto merge of #110160 - petrochenkov:notagain2, r=cjgillot

resolve: Pre-compute non-reexport module children

Instead of repeating the same logic by walking HIR during metadata encoding.

The only difference is that we are no longer encoding `macro_rules` items, but we never currently need them as a part of this list. They can be encoded separately if this need ever arises.

`module_reexports` is also un-querified, because I don't see any reasons to make it a query, only overhead.

Author: bors