[MM-60609][MM-60612] Include Desktop App metrics in PerformanceReporter, add metrics in Prometheus for CPU/Memory usage (#28825)

* [MM-60609][MM-60612] Include Desktop App metrics in PerformanceReporter, add metrics in Prometheus for CPU/Memory usage

* Fix mocks

* PR feedback

server/einterfaces/metrics.go

@@ -120,4 +120,6 @@ type MetricsInterface interface {
 	ObserveMobileClientTeamSwitchDuration(platform string, elapsed float64)
 	ClearMobileClientSessionMetadata()
 	ObserveMobileClientSessionMetadata(version string, platform string, value float64, notificationDisabled string)
+	ObserveDesktopCpuUsage(platform, version, process string, usage float64)
+	ObserveDesktopMemoryUsage(platform, version, process string, usage float64)
 }