Electrumx.utxo() should accept simpleledger addresses

[christroutner]

When passing an SLP address with a simpleledger: prefix, the Electrumx.utxo() method throws an error. It would be great if this endpoint could automatically convert any SLP addresses into a BCH address.

There are probably many other methods that could use this improvement. A DRY function that can be called should be created with really good unit tests. It should be able to handle both a single address and an array of addresses.