feat: add stdout and filesystem notification channels (#2925)

* feat: add filesystem and stdout notification channels

* configure through env vars

* compile

* feat: add compact option for debug notification channels

* fix channel mock generation

* avoid sensitive information in error message

Co-authored-by: Livio Amstutz <livio.a@gmail.com>

* add review improvements

Co-authored-by: Livio Amstutz <livio.a@gmail.com>

internal/notification/channels/mock/channel.mock.go

@@ -0,0 +1,48 @@
+// Code generated by MockGen. DO NOT EDIT.
+// Source: github.com/caos/zitadel/internal/notification/channels (interfaces: NotificationChannel)
+
+// Package mock is a generated GoMock package.
+package mock
+
+import (
+	channels "github.com/caos/zitadel/internal/notification/channels"
+	gomock "github.com/golang/mock/gomock"
+	reflect "reflect"
+)
+
+// MockNotificationChannel is a mock of NotificationChannel interface
+type MockNotificationChannel struct {
+	ctrl     *gomock.Controller
+	recorder *MockNotificationChannelMockRecorder
+}
+
+// MockNotificationChannelMockRecorder is the mock recorder for MockNotificationChannel
+type MockNotificationChannelMockRecorder struct {
+	mock *MockNotificationChannel
+}
+
+// NewMockNotificationChannel creates a new mock instance
+func NewMockNotificationChannel(ctrl *gomock.Controller) *MockNotificationChannel {
+	mock := &MockNotificationChannel{ctrl: ctrl}
+	mock.recorder = &MockNotificationChannelMockRecorder{mock}
+	return mock
+}
+
+// EXPECT returns an object that allows the caller to indicate expected use
+func (m *MockNotificationChannel) EXPECT() *MockNotificationChannelMockRecorder {
+	return m.recorder
+}
+
+// HandleMessage mocks base method
+func (m *MockNotificationChannel) HandleMessage(arg0 channels.Message) error {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "HandleMessage", arg0)
+	ret0, _ := ret[0].(error)
+	return ret0
+}
+
+// HandleMessage indicates an expected call of HandleMessage
+func (mr *MockNotificationChannelMockRecorder) HandleMessage(arg0 interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "HandleMessage", reflect.TypeOf((*MockNotificationChannel)(nil).HandleMessage), arg0)
+}