feat(prometheus): add metrics to Subsonic API and Plugins (#4266)

* Add prometheus metrics to subsonic and plugins

* address feedback, do not log error if operation is not supported

* add missing timestamp and client to stats

* remove .view from subsonic route

* directly inject DataStore in Prometheus, to avoid having to pass it in every call

Signed-off-by: Deluan <deluan@navidrome.org>

---------

Signed-off-by: Deluan <deluan@navidrome.org>
Co-authored-by: Deluan <deluan@navidrome.org>

plugins/manifest_permissions_test.go

@@ -55,7 +55,7 @@ var _ = Describe("Plugin Permissions", func() {
 	BeforeEach(func() {
 		DeferCleanup(configtest.SetupConfig())
 		ctx = context.Background()
-		mgr = createManager(nil)
+		mgr = createManager(nil, nil)
 		tempDir = GinkgoT().TempDir()
 	})