Replace a few for loops with foreach to avoid loop cloning (#15668)

Replace a few for loops with foreach to avoid loop cloning (#15668)

A pattern like
int len = a.Length;
for (int i = 0; i < len; i++) { ... a[i] ... }
may result in unnecessary loop cloning.

Anyway, there's no real reason to use a for loop in any of these case. Avois the need for a cast too.

Also remove duplicated code related to AppDomain.OnXResolveEvent method.