Add notifications for collector failures

[kaysond]

We should add an API endpoint so the collector can report smartctl --scan and smartctl --info errors. The endpoint can trigger an opt-out notification. If the backend receives a smartctl --xall json object indicating an error (see #944), a notification should also be sent.

This needs a new handler, a new route:

scrutiny/webapp/backend/pkg/web/server.go

Lines 22 to 53 in 9d1ce79

	func (ae *AppEngine) Setup(logger *logrus.Entry) *gin.Engine {
	r := gin.New()
	r.Use(middleware.LoggerMiddleware(logger))
	r.Use(middleware.RepositoryMiddleware(ae.Config, logger))
	r.Use(middleware.ConfigMiddleware(ae.Config))
	r.Use(gin.Recovery())
	basePath := ae.Config.GetString("web.listen.basepath")
	logger.Debugf("basepath: %s", basePath)
	base := r.Group(basePath)
	{
	api := base.Group("/api")
	{
	api.GET("/health", handler.HealthCheck)
	api.POST("/health/notify", handler.SendTestNotification) //check if notifications are configured correctly
	api.POST("/devices/register", handler.RegisterDevices) //used by Collector to register new devices and retrieve filtered list
	api.GET("/summary", handler.GetDevicesSummary) //used by Dashboard
	api.GET("/summary/temp", handler.GetDevicesSummaryTempHistory) //used by Dashboard (Temperature history dropdown)
	api.POST("/device/:wwn/smart", handler.UploadDeviceMetrics) //used by Collector to upload data
	api.POST("/device/:wwn/selftest", handler.UploadDeviceSelfTests)
	api.GET("/device/:wwn/details", handler.GetDeviceDetails) //used by Details
	api.POST("/device/:wwn/archive", handler.ArchiveDevice) //used by UI to archive device
	api.POST("/device/:wwn/unarchive", handler.UnarchiveDevice) //used by UI to unarchive device
	api.DELETE("/device/:wwn", handler.DeleteDevice) //used by UI to delete device
	api.GET("/settings", handler.GetSettings) //used to get settings
	api.POST("/settings", handler.SaveSettings) //used to save settings
	}
	}

and a new setting, including a UI element and database migration. See bdbe13e for an example.

[kaysond]

This probably needs a special case for #942