When adding seeds to AFL via cli, add them to shared corpus

[brunoproduit]

When using cargo ziggy add-seeds, we should also copy the seeds to shared_corpus

[vanhauser-thc]

No we should not because the seeds might be duplicates.
So afl-fuzz will pick those up that are not duplicates, there will den by synced to the corpus and picked up there by honggfuzz/libafl.
We could add them to honggfuzz' dynamic input queue though.