Datasource: Overhaul plugin error handling and action buttons (#67014)

* - initial work on data source config page

* - add links to test status box
- add tracking function

* - add test for the DataSourceConfigAlert component

* - fix flicker of the alert box

* - fix the build

* - small improvements

* - fix failing build

* - fix failing unit tests

* - prettier and betterer fixes

* - fix failing e2e tests

* - fix build again

* - rewrite solution according to the PR comments

* - cleanup

* - fix failing e2e

* - use absolute path in link

* Minor fixes

---------

Co-authored-by: Torkel Ödegaard <torkel@grafana.com>

public/app/features/dashboard/services/PublicDashboardDataSource.ts

@@ -5,6 +5,7 @@ import {
   DataQuery,
   DataQueryRequest,
   DataQueryResponse,
+  TestDataSourceResponse,
   DataSourceApi,
   DataSourceJsonData,
   DataSourcePluginMeta,
@@ -151,7 +152,7 @@ export class PublicDashboardDataSource extends DataSourceApi<DataQuery, DataSour
     return { data: [toDataFrame(annotations)] };
   }
 
-  testDatasource(): Promise<null> {
-    return Promise.resolve(null);
+  testDatasource(): Promise<TestDataSourceResponse> {
+    return Promise.resolve({ message: '', status: '' });
   }
 }