Use tx_type in Coin and Snapshot instead of fIsCoinbase

[frolosofsky]

Context Currently, node cannot operate after fast-sync because it cannot validate finalizer commit inputs as these checks perform GetTransaction that leads to reading block from the disk; but node doesn't have such a block when running in fast-sync mode. Finally, node rejects finalizer commits and ban its peers. On the other hand, snapshot transfers UTXO set which has all needed transactions but there is a lack of transaction type in UTXO representation that prevents from using it.

This PR fixes that by:

• adding transaction type to the UTXO set (via Coin and snapshot classes).
• performing UTXO lookup prior to GetTransaction() in esperanza::ContextualCheck*;

Fixes #547.

[frolosofsky]

Rebased with master, fixed compilation errors when ENABLE_USBDEVICE is on.

[frolosofsky]

@kostyantyn @Nizametdinov @Gnappuraz @scravy I've reacted on your comments and adjusted the code. Please take another look.