Allow inline enforcement of Page Manager configs

Problem/Motivation

We're using Page Manager to create custom page layouts. However, we don't get the Config Enforce fieldset that would allow us to enforce this config directly. A workaround is to enforce it from active config.

Steps to reproduce

1. Download and enable Page Manager
2. Create a Page
3. Observe that there is no way to enforce the config from these forms.

Proposed resolution

TBD