QuerayblePayload trait changes: delete Metadata args, etc

[ggutoski]

• The following methods of QueryablePayload take an unneeded arg of type Self::Metadata: len, iter, transaction_with_proof, and others.
  • May need to coordinate with [TECH DEBT] - BlockPayload trait delete Metadata args and return vals HotShot#3300
• transaction_with_proof desperately needs an arg of type VidCommon. Downstream currently has a horrible hack: https://github.com/EspressoSystems/espresso-sequencer/blob/26a6b299ce260a210e6fa3253bbd50fb57f3023d/sequencer/src/block/full_payload/payload.rs#L221-L229
• Is there a reason that TransactionIndex has a trait bound for Ord? Can it be deleted? (No big deal either way though.)