MM-52804 - Implement SendPushNotification plugin api method (#24273)

* add SendPushNotification plugin api method

* lint; add testing.Short bc of the sleep

* add interface and generated layers

* add fields to PluginPushNotification; generate mocks

* SendPushNotification -> SendPluginPushNotification; improved comments

* more comments; fix test

* send api.ctx

server/public/plugin/plugintest/api.go

@@ -3639,6 +3639,20 @@ func (_m *API) SendMail(to string, subject string, htmlBody string) *model.AppEr
 	return r0
 }
 
+// SendPluginPushNotification provides a mock function with given fields: notification
+func (_m *API) SendPluginPushNotification(notification *model.PluginPushNotification) error {
+	ret := _m.Called(notification)
+
+	var r0 error
+	if rf, ok := ret.Get(0).(func(*model.PluginPushNotification) error); ok {
+		r0 = rf(notification)
+	} else {
+		r0 = ret.Error(0)
+	}
+
+	return r0
+}
+
 // SetProfileImage provides a mock function with given fields: userID, data
 func (_m *API) SetProfileImage(userID string, data []byte) *model.AppError {
 	ret := _m.Called(userID, data)