Feat: Adds reconnect for failing datasource in Explore (#16226)

* Style: made outlined buttons and used it in Alert component

* Refactor: clean up state on load data source failure

* Refactor: test data source thunk created

* Refactor: move logic to changeDatasource and call that from intialize

* Refactor: move load explore datasources to own thunk

* Refactor: move logic to updateDatasourceInstanceAction

* Tests: reducer tests

* Test(Explore): Added tests and made thunkTester async

* Fix(Explore): Fixed so that we do not render StartPage if there is no StartPage

* Fix(Explore): Missed type in merge

* Refactor: Thunktester did not fail tests on async failures and prevented queires from running on datasource failures

* Feat: Fadein error alert to prevent flickering

* Feat: Refresh labels after reconnect

* Refactor: Move useLokiForceLabels into useLokiLabels from PR comments

* Feat: adds refresh metrics to Prometheus languageprovider

* Style: removes padding for connected datasources

* Chore: remove implicit anys

public/sass/components/_buttons.scss

@@ -123,7 +123,7 @@
   @include button-outline-variant($btn-inverse-bg);
 }
 .btn-outline-danger {
-  @include button-outline-variant(green);
+  @include button-outline-variant($btn-danger-bg);
 }
 
 .btn-outline-disabled {