Implement header union invalidation in the BMv2 back end.#4982

Draft

fruffy wants to merge 3 commits intomainfrom fruffy/bmv2_hu_fixes

+339-66

Commits on Oct 25, 2024

Set other headers also invalid when calling setInvalid on a union header.
fruffy
committed
Add an option to copy structures to skip expanding header unions.
fruffy
committed
Implement header union invaidation in the BMv2 back end.
fruffy
committed