Add configuration options for notifications

**Feature request**
It would be great to have serialization for data.

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

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

No file or test is named. Start by locating the configuration handling for `enable_serialization`, then determine which data needs serialization and where the option applies. Done means the option defaults to `false`, enables the requested serialization behavior, and has coverage for both settings.

Written by the indexing model from the issue text.