Refactor consensus.rs error mapping

[JoseSK999]

I have created a tx_err macro to succinctly build a TransactionError. This has the benefit of skipping the BlockValidationErrors:: enum prefix when specifying the error, and flexibly taking a third argument for the inner variant value.

Instead of:

return Err(TransactionError {
    txid: transaction.compute_txid(),
    error: BlockValidationErrors::NotEnoughMoney,
}
.into());

We do:

return Err(tx_err!(txid, NotEnoughMoney))?;

The validation methods now directly return TransactionError and use a lazily evaluated closure to compute the txid if there's an error.

The pub mod error line is now before pub mod consensus to make the macro available. Finally changed the "Invalid coinbase txid" error message to "Invalid Coinbase PrevOut".

This reduces the error mapping boilerplate in the most important consensus function.

What is the purpose of this pull request?

• Bug fix
• Documentation update
• New feature
• Test
• Other: Refactor and simplification

Which crates are being modified?

• floresta-chain
• floresta-cli
• floresta-common
• floresta-compact-filters
• floresta-electrum
• floresta-watch-only
• floresta-wire
• floresta
• florestad
• Other: .

[Davidson-Souza]

ACK b82de34