rpc: add dumptxoutset
rpc: add dumptxoutset

Allows the creation of a UTXO snapshot to disk.


Former-commit-id: 5f0c56fc71da4e97c6230d1d5e73bac0750b3a42
syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin