MM-36764 mlog refactor (#18118)

Refactor mlog
- simplify mlog by removing redundant code
- remove Zap dependency
- update unit test helpers
- update logging config
- update auditing

config/logconfigsrc_test.go

@@ -0,0 +1,49 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package config
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+const (
+	validJSON = `{"file":{ "Type":"file"}}`
+	badJSON   = `{"file":{ Type="file"}}`
+)
+
+func TestNewLogConfigSrc(t *testing.T) {
+	store := NewTestMemoryStore()
+	require.NotNil(t, store)
+	err := store.SetFile("advancedlogging.conf", []byte(validJSON))
+	require.NoError(t, err)
+
+	tests := []struct {
+		name        string
+		dsn         string
+		configStore *Store
+		wantErr     bool
+		wantType    LogConfigSrc
+	}{
+		{name: "empty dsn", dsn: "", configStore: store, wantErr: true, wantType: nil},
+		{name: "garbage dsn", dsn: "!@wfejwcevioj", configStore: store, wantErr: true, wantType: nil},
+		{name: "valid json dsn", dsn: validJSON, configStore: store, wantErr: false, wantType: &jsonSrc{}},
+		{name: "invalid json dsn", dsn: badJSON, configStore: store, wantErr: true, wantType: nil},
+		{name: "valid filespec dsn", dsn: "advancedlogging.conf", configStore: store, wantErr: false, wantType: &fileSrc{}},
+		{name: "invalid filespec dsn", dsn: "/nobody/here.conf", configStore: store, wantErr: true, wantType: nil},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := NewLogConfigSrc(tt.dsn, tt.configStore)
+			if tt.wantErr {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+				assert.IsType(t, tt.wantType, got)
+			}
+		})
+	}
+}