Update to work with changes in Configuration Provider

Problem/Motivation

The storage used by Configuration Provider was changed in #2954369: Inject storage into ::getInstallableConfig(). We need to change our usage of the storage.

At the same time, we can improve our design by moving from the current approach of serializing configuration updates into the plugin to loading them at runtime.

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes