Use pubkey as identifier in SignatureSetType

[l4l]

Description of the Change

ed25519 can have different signature for the same public key, so it necessary to guarantee uniqueness of each public key in signature set

[neewy]

This fix should contain test with text data based on modified version of ed25519

[luckychess]

Looks good overall but I agree with @neewy that we need some tests for this issue.

[l4l]

It is not really trivial to write the test for that case, as long as:

1. requires modification of iroha-ed25519
2. or there's a need somehow skip timeout check (that is not trivial at all)

[lebdron]

@l4l What kind of timeout check do you mean? It should be possible to create a transaction with TestTransactionBuilder, call addSignature with modified ed25519 signature, and pass this transaction as an input for some unit or integration test.

[l4l]

Good idea

[neewy]

Any progress? I've noticed you have added test in commit above, is it sufficient to review this fix?

[l4l]

Yes, for now only that test can be done without significant projects changes and I think better review&merge it asap, then think about other components (though, they will work as well, as they have code duplication actually)