[MM-64686] Expose audit logging functionality via plugin API (#31204)

This commit exposes audit logging functionality to plugins via the plugin API, allowing plugins to create and log audit records. Additionally, it addresses a gob encoding issue that could cause plugin crashes when audit data contains nil pointers or unregistered types.

server/public/plugin/plugintest/api.go

@@ -8,6 +8,8 @@ import (
 	io "io"
 	http "net/http"
 
+	logr "github.com/mattermost/logr/v2"
+
 	mock "github.com/stretchr/testify/mock"
 
 	model "github.com/mattermost/mattermost/server/public/model"
@@ -4312,6 +4314,16 @@ func (_m *API) LoadPluginConfiguration(dest interface{}) error {
 	return r0
 }
 
+// LogAuditRec provides a mock function with given fields: rec
+func (_m *API) LogAuditRec(rec *model.AuditRecord) {
+	_m.Called(rec)
+}
+
+// LogAuditRecWithLevel provides a mock function with given fields: rec, level
+func (_m *API) LogAuditRecWithLevel(rec *model.AuditRecord, level logr.Level) {
+	_m.Called(rec, level)
+}
+
 // LogDebug provides a mock function with given fields: msg, keyValuePairs
 func (_m *API) LogDebug(msg string, keyValuePairs ...interface{}) {
 	var _ca []interface{}