Handle edge cases in filtering

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

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

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

No files, tests, or entry points are named. Start by locating parser filtering and the configuration definitions, then determine what “search for parsers” should search and return. Done means the new enable_search option defaults to false and the agreed parser-search behavior is covered by tests.

Written by the indexing model from the issue text.