node-data: change hash method on transaction to digest

[Neotamandua]

Summary

Transaction hash and transaction ID are often used as semantically equivalent terms in the crypto/blockchain world. To avoid any ambiguity, we should refrain from employing the terms "hash" and "id" in a manner that result in their denotations having different meanings (different hashes/values).

Relevant Context

• The value of hash(&self) is only being used in the Merkle tree.
• The value of id(&self) is the actual transaction identifier being used in the explorer, wallet, to identify transactions etc. - This is the equivalent of the txID/txHash terminology on other chains.

rusk/node-data/src/ledger/transaction.rs

Lines 57 to 81 in 08f95c3

	impl Transaction {
	/// Computes the hash of the transaction.
	///
	/// This method returns the hash of the entire
	/// transaction in its serialized form
	///
	/// ### Returns
	/// An array of 32 bytes representing the hash of the transaction.
	pub fn hash(&self) -> [u8; 32] {
	sha3::Sha3_256::digest(self.inner.to_var_bytes()).into()
	}
	/// Computes the transaction ID.
	///
	/// The transaction ID is a unique identifier for the transaction.
	/// Unlike the [`hash()`](#method.hash) method, which is computed over the
	/// entire transaction, the transaction ID is derived from specific
	/// fields of the transaction and serves as a unique identifier of the
	/// transaction itself.
	///
	/// ### Returns
	/// An array of 32 bytes representing the transaction ID.
	pub fn id(&self) -> [u8; 32] {
	self.inner.hash().to_bytes()
	}

Possible Solution (optional)

As hash(&self) is rarely used and is not really needed by end-users or integrators, we should introduce another name for it (potentially digest) so that the value of id(&self) can be safely referred to as TxID or TxHash.