Search: Fixes search limits and adds a page parameter (#16458)

* Search: Fixes search limits and adds a page parameter

This adds a page parameter to search api without adding
any major breaking change.

It does at an api validation error when trying to use
a limit beyond 5000. This is a breaking change. We could
remove this and have it only in the docs and describe that this
is a limit that grafana will apply silently.

Fixes #16049

* Fix: Corrected wrong array slice change

* Docs: minor docs fix

* Search: fixed folder tests

* Fixed: Moved limit to correct inner query

* Search: moving limit check and page check

* Search: limit in handler is no longer needed

docs/sources/http_api/folder_dashboard_search.md

@@ -23,7 +23,8 @@ Query parameters:
 - **dashboardIds** – List of dashboard id's to search for
 - **folderIds** – List of folder id's to search in for dashboards
 - **starred** – Flag indicating if only starred Dashboards should be returned
-- **limit** – Limit the number of returned results
+- **limit** – Limit the number of returned results (max 5000)
+- **page** – Use this parameter to access hits beyond limit. Numbering starts at 1. limit param acts as page size.
 
 **Example request for retrieving folders and dashboards of the general folder**:
 
@@ -95,4 +96,4 @@ Content-Type: application/json
     "uri":"db/production-overview" // deprecated in Grafana v5.0
   }
 ]
-```
+```