Improve UtxoSearch

[mmontin]

UtxoSearch is a nice feature to browse through existing on-chain utxos. However, its usage is still tedious: utxo searches need to be run, and filters are not embedded in the search itself. It addition, the monadic capabilities of the search are seldom used. We need to investigate a better way of searching through utxos with builtin filters and usable monadic capabilities (or no monadic capabilities at all).