T2447
Depends on D11967
Update sendXec function and the functions it relies on to generate and send an XEC transaction with the new chronik utxo storage format.
Key differences: chronik utxos have an outpoint key with the vout at outIdx. The txid is also included in this outpoint object.
Also, while chronik utxos still have a value key, it is string type. Transaction builder utxo signing requires this to be a number.
This diff also modifies mocks used by unit tests to have the new chronik format.