Add configuration options for search

**Feature request**
It would be great to have filtering for api.

**Use case**
Many users need this functionality for production deployments.

**Implementation idea**
Add a new config option `enable_filtering` with default `false`.

Start by locating the configuration handling and the API search entry point in the repository. Determine how search requests are filtered and where configuration defaults are defined. Done means a documented `enable_filtering` option defaults to `false` and API search filtering works when it is enabled.

Written by the indexing model from the issue text.