Add revive to the list of linters.

[cenkalti]

Part of "Enhance the static-analysis workflow" issue. #14164

The list of issues found and fixed were:

[dev:etcd]{main}% make lint
golangci-lint run
tools/etcd-dump-logs/etcd-dump-log_test.go:47:2: var-naming: don't use underscores in Go names; var decoder_correctoutputformat should be decoderCorrectoutputformat (revive)
        decoder_correctoutputformat := filepath.Join(binDir, "/testdecoder/decoder_correctoutputformat.sh")
        ^
tools/etcd-dump-logs/etcd-dump-log_test.go:48:2: var-naming: don't use underscores in Go names; var decoder_wrongoutputformat should be decoderWrongoutputformat (revive)
        decoder_wrongoutputformat := filepath.Join(binDir, "/testdecoder/decoder_wrongoutputformat.sh")
        ^
tools/etcd-dump-logs/main.go:93:4: var-naming: var confstateJson should be confstateJSON (revive)
                        confstateJson, err := json.Marshal(snapshot.Metadata.ConfState)
                        ^
tools/etcd-dump-logs/main.go:375:4: var-naming: don't use underscores in Go names; var decoder_status should be decoderStatus (revive)
                        decoder_status, decoded_data := parseDecoderOutput(decoderoutput)
                        ^
tools/etcd-dump-logs/main.go:396:6: var-naming: don't use underscores in Go names; var decoder_status should be decoderStatus (revive)
        var decoder_status string
            ^
tools/etcd-dump-logs/main.go:397:6: var-naming: don't use underscores in Go names; var decoded_data should be decodedData (revive)
        var decoded_data string
            ^
contrib/raftexample/httpapi.go:63:3: var-naming: var nodeId should be nodeID (revive)
                nodeId, err := strconv.ParseUint(key[1:], 0, 64)
                ^
contrib/raftexample/httpapi.go:79:3: var-naming: var nodeId should be nodeID (revive)
                nodeId, err := strconv.ParseUint(key[1:], 0, 64)
                ^
contrib/raftexample/httpapi.go:104:6: var-naming: func serveHttpKVAPI should be serveHTTPKVAPI (revive)
func serveHttpKVAPI(kv *kvstore, port int, confChangeC chan<- raftpb.ConfChange, errorC <-chan error) {
     ^
tools/benchmark/cmd/util.go:50:2: var-naming: var leaderId should be leaderID (revive)
        leaderId := uint64(0)
        ^
make: *** [lint] Error 1

[ahrtr]

LGTM

Thank you @cenkalti