PPX-01 add verification of vote signer belonging to masternodes

[wgr523]

Proposed changes

PPX-01 add verification of vote signer belonging to masternodes.

Types of changes

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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)
• Regular KTLO or any of the maintaince work. e.g code style
• CICD Improvement

Impacted Components

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• Consensus
• Account
• Network
• Geth
• Smart Contract
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Checklist

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• This PR has sufficient test coverage (unit/integration test) OR I have provided reason in the PR description for not having test coverage
• Provide an end-to-end test plan in the PR description on how to manually test it on the devnet/testnet.
• Tested the backwards compatibility.
• Tested with XDC nodes running this version co-exist with those running the previous version.
• Relevant documentation has been updated as part of this PR
• N/A

[gzliudan]

Shall we let the function verifyVotes return error and check it in the function voteHandler ?

[liam-lai]

It's better change at VerifyVoteMessage function to stop candidate but not masternodes write as signer.

[wgr523]

Shall we let the function verifyVotes return error and check it in the function voteHandler ?

the code changed is inside a go routine. the action inside the routine should be clearing the signature. after that, subsequent function can return error if the signature is empty, or not use that vote in a QC.