Do not verify VCs twice in the enveloped VC case #116
Description
This code path verifies VCs twice when they may have already been verified when the enveloped VP was verified. We should try to prevent this duplication:
https://github.com/digitalbazaar/bedrock-vc-verifier/blob/v23.4.0/lib/verify.js#L116-L125
It might be that this code path is meant to cover something similar to the situation covered here:
https://github.com/digitalbazaar/bedrock-vc-verifier/blob/v23.4.0/lib/verify.js#L49-L72
Where there are also enveloped VCs that need verification.
Ideally the verification code paths can be better unified generally such that they are more intuitive and easier to maintain.