Plugins: Support for link extensions (#61663)

* added extensions to plugin.json and exposing it via frontend settings.

* added extensions to the plugin.json schema.

* changing the extensions in frontend settings to a map instead of an array.

* wip

* feat(pluginregistry): begin wiring up registry

* feat(pluginextensions): prevent duplicate links and clean up

* added test case for link extensions.

* added tests and implemented the getPluginLink function.

* wip

* feat(pluginextensions): expose plugin extension registry

* fix(pluginextensions): appease the typescript gods post rename

* renamed file and will throw error if trying to call setExtensionsRegistry if trying to call it twice.

* added reafactorings.

* fixed failing test.

* minor refactorings to make sure we only include extensions if the app is enabled.

* fixed some nits.

* Update public/app/features/plugins/extensions/registry.test.ts

Co-authored-by: Levente Balogh <balogh.levente.hu@gmail.com>

* Update packages/grafana-runtime/src/services/pluginExtensions/registry.ts

Co-authored-by: Levente Balogh <balogh.levente.hu@gmail.com>

* Update packages/grafana-runtime/src/services/pluginExtensions/registry.ts

Co-authored-by: Levente Balogh <balogh.levente.hu@gmail.com>

* Update public/app/features/plugins/extensions/registry.test.ts

Co-authored-by: Levente Balogh <balogh.levente.hu@gmail.com>

* Moved types for extensions from data to runtime.

* added a small example on how you could consume link extensions.

* renamed after feedback from levi.

* updated the plugindef.cue.

* using the generated plugin def.

* added tests for apps and extensions.

* fixed linting issues.

* wip

* wip

* wip

* wip

* test(extensions): fix up failing tests

* feat(extensions): freeze registry extension arrays, include type in registry items

* added restrictions in the pugindef cue schema.

* wip

* added required fields.

* added key to uniquely identify each item.

* test(pluginextensions): align tests with implementation

* chore(schema): refresh reference.md

---------

Co-authored-by: Jack Westbrook <jack.westbrook@gmail.com>
Co-authored-by: Levente Balogh <balogh.levente.hu@gmail.com>

public/app/features/sandbox/TestStuffPage.tsx

@@ -3,8 +3,9 @@ import { useObservable } from 'react-use';
 import AutoSizer from 'react-virtualized-auto-sizer';
 
 import { ApplyFieldOverrideOptions, dateMath, FieldColorModeId, NavModelItem, PanelData } from '@grafana/data';
+import { getPluginExtensions } from '@grafana/runtime';
 import { DataTransformerConfig } from '@grafana/schema';
-import { Button, Table } from '@grafana/ui';
+import { Button, HorizontalGroup, LinkButton, Table } from '@grafana/ui';
 import { Page } from 'app/core/components/Page/Page';
 import { config } from 'app/core/config';
 import { useAppNotification } from 'app/core/copy/appNotification';
@@ -60,6 +61,9 @@ export const TestStuffPage = () => {
   return (
     <Page navModel={{ node: node, main: node }}>
       <Page.Contents>
+        <HorizontalGroup>
+          <LinkToBasicApp target="grafana/sandbox/testing" />
+        </HorizontalGroup>
         {data && (
           <AutoSizer style={{ width: '100%', height: '600px' }}>
             {({ width }) => {
@@ -144,4 +148,24 @@ export function getDefaultState(): State {
   };
 }
 
+function LinkToBasicApp({ target }: { target: string }) {
+  const { extensions, error } = getPluginExtensions({ target });
+
+  if (error) {
+    return null;
+  }
+
+  return (
+    <div>
+      {extensions.map((extension) => {
+        return (
+          <LinkButton href={extension.href} title={extension.description} key={extension.key}>
+            {extension.title}
+          </LinkButton>
+        );
+      })}
+    </div>
+  );
+}
+
 export default TestStuffPage;