Consider deprecating old controllers API

**Feature request**
It would be great to have search for core.

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

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

No file or test is named. Start by tracing how configuration options are declared and consumed, then identify the existing core or controller search entry point. Done means defining the `enable_search` option with a default of `false` and agreeing on the intended search behavior for core.

Written by the indexing model from the issue text.