replication: decode heartbeat events

[dveeden]

Issue: #1068

Tested with:

diff --git a/cmd/go-mysqlbinlog/main.go b/cmd/go-mysqlbinlog/main.go
index 8d322c3..3432e5f 100644
--- a/cmd/go-mysqlbinlog/main.go
+++ b/cmd/go-mysqlbinlog/main.go
@@ -9,6 +9,7 @@ import (
        "fmt"
        "log/slog"
        "os"
+       "time"
 
        "github.com/pingcap/errors"
 
@@ -51,6 +52,8 @@ func main() {
                SemiSyncEnabled:      *semiSync,
                UseDecimal:           true,
                MaxReconnectAttempts: 10,
+               HeartbeatPeriod:      time.Second * 10,
+               DumpCommandFlag:      replication.USE_HEARTBEAT_EVENT_V2,
        }
 
        logOpts := &slog.HandlerOptions{

This now reports:

=== HeartbeatLogEventV2 ===
Date: 1970-01-01 01:00:00
Log position: 158
Event size: 42
Heartbeat Event Version: 2
Binlog File Name: binlog.000001
Binlog Offset: 158