Display vote validity in listgovproposals and add validity filter

[shohamc1]

What kind of PR is this?:

/kind feature

What this PR does / why we need it:

• New valid field in vote output - denotes whether the vote is valid at cycle end
• New valid argument to show only valid/invalid votes (defaults to show only valid votes)

Usage:

Show valid votes:

$ defi-cli listgovproposalvotes propId "all" 1 "{}" False True
[{'proposalId': 'e686c4205d893f1883652855ad957a71083a0dbd19e97bfacaf88fc9ceb5c642', 'masternodeId': '18a2c79448e8feeed9ee3e6a5ea9b2640062557ddac8e9ac2ee04f62ed484f24', 'cycle': 1, 'vote': 'YES', 'valid': True}, {'proposalId': 'e686c4205d893f1883652855ad957a71083a0dbd19e97bfacaf88fc9ceb5c642', 'masternodeId': '3a64ec587a39d3f5b1e1944c6f800709453ce8fe7a65a63cec8cc2dd26ad8671', 'cycle': 1, 'vote': 'YES', 'valid': True}, {'proposalId': 'e686c4205d893f1883652855ad957a71083a0dbd19e97bfacaf88fc9ceb5c642', 'masternodeId': 'e86c027861cc0af423313f4152a44a83296a388eb51bf1a6dde9bd75bed55fb4', 'cycle': 1, 'vote': 'YES', 'valid': True}]

Show invalid votes:

$ defi-cli listgovproposalvotes propId "all" 1 "{}" False False
[{'proposalId': '55684409f1cecd6dd7b16139be88993ced9a671f8682075a206452c1a16f8b01', 'masternodeId': '35db8101a4fb72d27af93622a20cdfee160466112252ac2866d5ccd564b55b25', 'cycle': 1, 'vote': 'YES', 'valid': False}]

Additional comments?:

Port of #1725