Resolve #2744905 "Support permanent inline-image files within answer text"

Temporary code solution to enable support for inline-image file permanent status - to be controlled by core's editor module.

This approach makes use of Core's editor module's inline-image support for non-core textfields. See Core Issue #2857444: Editor module fails to track usage of files embedded in non-core fields.

In addition, because faqfield has a custom data structure for the answer field, the keys would prevent core's code from successfully getting the answer image file paths. See Core's editor module code. Ideally the faqfield module would need to be re-factored entirely. The approach taken here would support this new functionality without having to refactor the entire module's field structure.

Closes #2744905