MM-22273 New auditing system (phase 1) (#13967)

* New auditing API outputting to syslog via TLS

* New config section for specifying remote syslog server IP, port, and cert.

* Legacy audit API retained for access history feature

audit/record.go

@@ -0,0 +1,37 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package audit
+
+// Meta represents metadata that can be added to a audit record as name/value pairs.
+type Meta map[string]interface{}
+
+// Record provides a consistent set of fields used for all audit logging.
+type Record struct {
+	APIPath   string
+	Event     string
+	Status    string
+	UserID    string
+	SessionID string
+	Client    string
+	IPAddress string
+	Meta      Meta
+}
+
+// Success marks the audit record status as successful.
+func (rec *Record) Success() {
+	rec.Status = Success
+}
+
+// Success marks the audit record status as failed.
+func (rec *Record) Fail() {
+	rec.Status = Fail
+}
+
+// AddMeta adds a single name/value pair to this audit record's metadata.
+func (rec *Record) AddMeta(name string, val interface{}) {
+	if rec.Meta == nil {
+		rec.Meta = Meta{}
+	}
+	rec.Meta[name] = val
+}