If already voted for a delegate(s), it does not say which one(s)

[chauey]

Expected behaviour

If user selects 1 or more delegates they already voted for and try to vote, it should tell the user which exact delegate(s) has already been voted for.

Actual behaviour

Right now, there is only a generic message and we can't tell which delegate(s) was already voted for.

Steps to reproduce

Vote again for a delegate (easier from other bug where the recently voted for delegate is not reflected and unchecked) and choose more delegates that are not voted for, but the error message is so generic, we don't know which delegate(s) was already voted for.

[slaweet]

I've created an issue in Lisk Core LiskArchive/lisk-sdk#781 to improve the error message. Moreover, after fixing #720 users should not see this message under usual circumstances (that is, unless they vote from two clients/computers at the same time). So I'm closing this issue