Remove the ability to select more than one for random sampling

[torao]

Description

This PR relates to #543, which removes voter selection. It removes the currently unused processing within the random sampling function and integrates it with the proposer selection. Multiple sampling was originally intended to select more than one in voter selection, but in practice, voters were selected in other ways and only used to select one proposer.

• The processing of the RandomSamplingWithPriority() function has been moved to SelectProposer(). This removes the check, as it's able to guarantee that the totalVotingPower is the sum of the VotingPower.
• Candidate interface that is no longer required has been removed.

I originally intended to remove SplitMix64 because I thought we could just use LastProofHash as a random number, but in reality, we need to use random numbers based on height and round in addition to LastProofHash, so SplitMix64 is still used (and therefore remains compatible with the previous behavior).

Closes: #XXX

[codecov]

Codecov Report

Merging #563 (f17c312) into main (5aca894) will decrease coverage by 0.11%.
The diff coverage is 92.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #563      +/-   ##
==========================================
- Coverage   66.17%   66.07%   -0.11%     
==========================================
  Files         278      277       -1     
  Lines       37022    36969      -53     
==========================================
- Hits        24499    24426      -73     
- Misses      10763    10775      +12     
- Partials     1760     1768       +8     

Impacted Files	Coverage Δ
types/validator_set.go	91.13% <92.00%> (+0.62%)	⬆️
privval/socket_listeners.go	79.72% <0.00%> (-4.06%)	⬇️
privval/signer_listener_endpoint.go	88.88% <0.00%> (-2.39%)	⬇️
consensus/state.go	71.40% <0.00%> (-1.36%)	⬇️
p2p/conn/connection.go	79.80% <0.00%> (-0.58%)	⬇️
consensus/reactor.go	74.44% <0.00%> (-0.18%)	⬇️
light/client.go	72.64% <0.00%> (-0.15%)	⬇️
p2p/pex/pex_reactor.go	79.67% <0.00%> (ø)
proxy/multi_app_conn.go	47.66% <0.00%> (ø)
... and 2 more

[torao]

@zemyblue
I think it seems that the voteSet parameter cannot be removed from this MakeCommit (it's the same code for Tendermint). Is there any reason why it should?

[zemyblue]

@zemyblue
I think it seems that the voteSet parameter cannot be removed from this MakeCommit (it's the same code for Tendermint). Is there any reason why it should?

Yes, no problem. I misunderstood and wrote it. Thank you.