ratelimit or limit queries to elasticsearch

## What & Why
Have the ability to ratelimit the search for users OR be able to deny queries that will create a high load on the storage backend.

Ratelimit should be X per time OR the ability that a new search can be only done if the previous returned.

The ability to deny queries that are known to be bad for the cluster would be the other option.

Both have the goal to avoid storage/elasticsearch down because of uneducated queries or impatience of users.

## Your Environment

* Graylog Version: 3.3

[z#843492]