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

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

pkg/api/plugins.go

@@ -208,6 +208,7 @@ func (hs *HTTPServer) GetPluginSettingByID(c *contextmodel.ReqContext) response.
 		SignatureOrg:     plugin.SignatureOrg,
 		SecureJsonFields: map[string]bool{},
 		AngularDetected:  plugin.Angular.Detected,
+		LoadingStrategy:  hs.pluginAssets.LoadingStrategy(c.Req.Context(), plugin),
 	}
 
 	if plugin.IsApp() {