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>

packages/grafana-runtime/src/config.ts

@@ -17,6 +17,7 @@ import {
   SystemDateFormatSettings,
   getThemeById,
   AngularMeta,
+  PluginLoadingStrategy,
 } from '@grafana/data';
 
 export interface AzureSettings {
@@ -40,6 +41,7 @@ export type AppPluginConfig = {
   version: string;
   preload: boolean;
   angular: AngularMeta;
+  loadingStrategy: PluginLoadingStrategy;
 };
 
 export type PreinstalledPlugin = {