Alerting: Integrate alerts with folders (#45763)

* Add Alert rules tab

* Add pagination and a simple name-based filtering

* Add name and label based filtering

* Improve pagination, handle the no results case

* Add tests for alerts folder view

* Add label filtering by clicking a tag

* Add tests for matcher to string method

* Add sorting, improve styles

* Use simple Select component for sorting

* Update default page size

* Remove unused code

* Use existingc thunk

* chore: update swagger spec

* Revert "chore: update swagger spec"

This reverts commit ee79ec7341.

* Code cleanup

* Fix ts

Co-authored-by: gillesdemey <gilles.de.mey@gmail.com>

public/app/core/utils/query.ts

@@ -46,3 +46,13 @@ function getRefId(num: number): string {
     return getRefId(Math.floor(num / letters.length) - 1) + letters[num % letters.length];
   }
 }
+
+/**
+ * Returns the input value for non empty string and undefined otherwise
+ *
+ * It is inadvisable to set a query param to an empty string as it will be added to the URL.
+ * It is better to keep it undefined so the param won't be added to the URL at all.
+ */
+export function getQueryParamValue(value: string | undefined | null): string | undefined {
+  return value || undefined;
+}