I want a function to BlockService calculating merkleComponentHash from TransactionHashe and cosigner PublicKey.

[xembook]

1. Expected behavior and actual behavior.

If I want to use BlockService.validateInBlock , merkleComponentHash must be calculated from TransactionHash in advance.
I think it would be useful if validateInBlock works just by specifying transactionInfo.

2. Steps to reproduce the problem.

I have confirmed that I can calculate merkleComponentHash by inserting the following logic.
However, I have no idea what kind of interface I should use.

var leaf = transactionHash;
if( cosignatures !== undefined && cosignatures.length > 0){

	const hasher = jssha3.sha3_256.create();
	hasher.update(Buffer.from(transactionHash, 'hex'));
	for (cosignature of cosignatures ){

		hasher.update(Buffer.from(cosignature.signer.publicKey, 'hex'));
	}
	leaf = hasher.hex().toUpperCase();
}

I'm in no particular hurry.
Please consider this.thanks.

[rg911]

Related to #481