MM-11029 Adding plugin logging functionality. (#9034)

* Capturing stdout, stderr of plugins in logs.

* Cleanup go-plugin debug logs.

* Adding logging to plugin API

* Generating mocks.

* godoc convention

mlog/stdlog.go

@@ -4,6 +4,7 @@
 package mlog
 
 import (
+	"bytes"
 	"strings"
 
 	"go.uber.org/zap"
@@ -72,3 +73,15 @@ func getStdLogOption() zap.Option {
 		},
 	)
 }
+
+type loggerWriter struct {
+	logFunc func(msg string, fields ...Field)
+}
+
+func (l *loggerWriter) Write(p []byte) (int, error) {
+	trimmed := string(bytes.TrimSpace(p))
+	for _, line := range strings.Split(trimmed, "\n") {
+		l.logFunc(string(line))
+	}
+	return len(p), nil
+}