Plugins: Introduce LoadingStrategy for frontend loading logic (#92392)

* do it all

* feat(plugins): move loadingStrategy to ds pluginMeta and add to plugin settings endpoint

* support child plugins and update tests

* use relative path for nested plugins

* feat(plugins): support nested plugins in the plugin loader cache by extracting pluginId from path

* feat(grafana-data): add plugin loading strategy to plugin meta and export

* feat(plugins): pass down loadingStrategy to fe plugin loader

* refactor(plugins): make PluginLoadingStrategy an enum

* feat(plugins): add the loading strategy to the fe plugin loader cache

* feat(plugins): load fe plugin js assets as script tags based on be loadingStrategy

* add more tests

* feat(plugins): add loading strategy to plugin preloader

* feat(plugins): make loadingStrategy a maybe and provide fetch fallback

* test(alerting): update config.apps mocks to include loadingStrategy

* fix format

---------

Co-authored-by: Jack Westbrook <jack.westbrook@gmail.com>

pkg/services/pluginsintegration/pluginstore/plugins.go

@@ -16,6 +16,7 @@ type Plugin struct {
 	Class plugins.Class
 
 	// App fields
+	Parent          *ParentPlugin
 	IncludedInAppID string
 	DefaultNavURL   string
 	Pinned          bool
@@ -59,7 +60,7 @@ func ToGrafanaDTO(p *plugins.Plugin) Plugin {
 		supportsStreaming = true
 	}
 
-	return Plugin{
+	dto := Plugin{
 		fs:                p.FS,
 		supportsStreaming: supportsStreaming,
 		Class:             p.Class,
@@ -76,4 +77,14 @@ func ToGrafanaDTO(p *plugins.Plugin) Plugin {
 		ExternalService:   p.ExternalService,
 		Angular:           p.Angular,
 	}
+
+	if p.Parent != nil {
+		dto.Parent = &ParentPlugin{ID: p.Parent.ID}
+	}
+
+	return dto
+}
+
+type ParentPlugin struct {
+	ID string
 }