Plugins: Add /meta and /metas APIs to plugins app (#113775)

* add /meta and /metas APIs

* wrapped storage route

* format file

* fix switch statement lint issue

* fix plugininstaller test

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Co-authored-by: Todd Treece <todd.treece@grafana.com>

pkg/plugins/models.go

@@ -238,6 +238,7 @@ type ReleaseState string
 
 const (
 	ReleaseStateAlpha ReleaseState = "alpha"
+	ReleaseStateBeta  ReleaseState = "beta"
 )
 
 type SignatureType string