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/dtos/plugins.go

@@ -28,6 +28,7 @@ type PluginSetting struct {
 	SignatureType   plugins.SignatureType   `json:"signatureType"`
 	SignatureOrg    string                  `json:"signatureOrg"`
 	AngularDetected bool                    `json:"angularDetected"`
+	LoadingStrategy plugins.LoadingStrategy `json:"loadingStrategy"`
 }
 
 type PluginListItem struct {