Add to query in a Saved Search

## What and why ?
A common task for Graylog users involves pivoting from one Saved Search to another. For example, a user would :
1. Load Saved Search 1
2. Search for a particular IP address in Saved Search 1
3. Deduce the username associated with that IP address
4. Load Saved Search 2
5. Search for the deduced username in Saved Search 2
6. Etc.

To reduce the time and effort spent in pivoting from one saved search to another, the idea of this feature request is to add an extra option similar to "Add to query", named "Add to query in a saved search" (see example in picture below).

When selecting this new option, the user would be prompted to select one of his Saved Searches, where the query will be added.


## Your Environment
* Graylog Version: 4.2.1