Integrate full relay with existing utils

[gregdhill]

I also think for next steps it could be good to integrate this code with BitcoinTx.sol and WitnessTx.sol (specifically validateWitnessProof) since I think that will let projects do some interesting things with Ordinals in the future.

Originally posted by @gregdhill in #273 (review)

Depends on #285

[nakul1010]

Using FullRelay instead of LightRelay in BitcoinTx.sol and WitnessTx.sol will break all the marketplace contracts, as they depend on LightRelay. Would you prefer to:

• Keep separate utility files, such as:
  • BitcoinFullRelayTx.sol & WitnessFullRelayTx.sol
  • BitcoinLightRelayTx.sol & WitnessLightRelayTx.sol
  • This approach avoids breaking the marketplace contracts.

OR

• Use FullRelay in BitcoinTx.sol and WitnessTx.sol and update the marketplace contracts to use FullRelay.