Implement UTXO Return Address RPC command

[coderofstuff]

Specifications

Info	Description
RPC Op	GetUtxoReturnAddress
Input	txid: Hash and accepting_block_daa_score: u64*
Output	Result<Address, ReturnAddressError>**

Notes

• *A holder of a UTXO will always know the transaction id that UTXO came from and the DAA score of the accepting block
• **When this call finds an address, it is guaranteed that the address is from the first input of the transaction that produced your UTXO. If the algorithm cannot find a return address (there are many reasons why it might not be able to), result in a ReturnAddressError.

Proto

GetUtxoReturnAddressRequestMessage getUtxoReturnAddressRequest = 1112;
GetUtxoReturnAddressResponseMessage getUtxoReturnAddressResponse = 1113;

[D-Stacks]

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[KaffinPX]

Could we separate accepting block finder/iterator and return address finder on consensus to possibly allow getTransactionCurrentAcceptingBlockin future to make transaction confirmation tracking simpler.