Introduce TxInput::OrderAccountCommand without nonces

[azarovh]

• Filled amount is now calculated based on the original ask/give price. This makes fill operations commutative. Though it has a negative consequence as potential remainder amounts, resulting in dust utxos produced on conclude, I don't think it's a major problem.

• It is forbidden to fill order with 0 to enforce spending utxo in a tx making it unique and not replayable.

• Nonce for AccountCommand::FillOrder is ignored. This is a bit hacky because nonce is still present making it confusing. But I think that this is more like an exception and refactoring out nonce from TxInput::AccountCommand seems like not worth it.

• Nonce for AccountCommand::ConcludeOrder is kept. Also I'm planning to keep it for the upcoming AccountCommand::FreezeOrder. Though it seems like it can be removed I don't see a point in doing it.

• Ignoring nonce forced me to add fork logic to TransactionVerifier::disconnect_transaction function because we don't need to decrement nonce for fill orders after the fork.

• Same fork logic goes into api-server and wallet. Though for wallet it required changing OutputCache logic which looks messy and I'm don't quite like it (alternative solution below can fix that).

UPDATE:

• Introduced new TxInput::OrderAccountCommand with FillOrder and ConcludeOrder commands.
• Nonces for OrderAccountCommand are completely removed.
• OrderAccountCommand::ConcludeOrder now contains remaining amounts that can be withdrawn from an account so that these amount can be used by hw wallet and also get into a signature. Also these amounts are checked in TransactionVerifier