Fix module override for recursive generic signatures (#24707)

Fix module override for recursive generic signatures (#24707)

* Fix module override for recursive generic signatures

When crossgen-ing with large version bubble enabled, generic signatures
that got copied from the source IL were missing module overrides at
deeper levels of the generic signature.
For example, in case of X<Y<A,B>,Z>, the override was applied only to Y
and Z, but not to A and B.

This change fixes that by inserting module override zapsig at all
levels.