[MM-54319] Add AdvancedLoggingJSON setting to system console (#24733)

* Add AdvancedLoggingJSON setting to system console

* Apply suggestions from code review

Co-authored-by: Doug Lauder <wiggin77@warpmail.net>

* Add validation for AdvancedLoggingJSON

---------

Co-authored-by: Doug Lauder <wiggin77@warpmail.net>
Co-authored-by: Mattermost Build <build@mattermost.com>

server/public/shared/mlog/mlog.go

@@ -7,7 +7,6 @@ package mlog
 import (
 	"context"
 	"encoding/json"
-	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -16,6 +15,8 @@ import (
 	"sync/atomic"
 	"time"
 
+	"github.com/pkg/errors"
+
 	"github.com/mattermost/logr/v2"
 	logrcfg "github.com/mattermost/logr/v2/config"
 )
@@ -68,6 +69,21 @@ func (lc LoggerConfiguration) Append(cfg LoggerConfiguration) {
 	}
 }
 
+func (lc LoggerConfiguration) IsValid() error {
+	logger, err := logr.New()
+	if err != nil {
+		return errors.Wrap(err, "failed to create logger")
+	}
+	defer logger.Shutdown()
+
+	err = logrcfg.ConfigureTargets(logger, lc, nil)
+	if err != nil {
+		return errors.Wrap(err, "logger configuration is invalid")
+	}
+
+	return nil
+}
+
 func (lc LoggerConfiguration) toTargetCfg() map[string]logrcfg.TargetCfg {
 	tcfg := make(map[string]logrcfg.TargetCfg)
 	for k, v := range lc {