Allow Accordion Title h2-h6

Problem/Motivation

I have existing content with accordion titles using headers of various levels. My users' siteimprove reports note whenever the content hierarchy is incorrect for a page, so they need the flexibility to select the right header level otherwise they get dinged in their reports as bugs they need to fix.

Now accordion title headers that are not h4s get deleted in the editor. I need to not lose content.

I made a patch against 3.1.3 adding schemas for accordion titles with different heading levels and dispatchers and conversions for each heading level. The changes in 3.1.5 broke my updates and I am wondering if this is still the best approach to adding the ability to use a range of heading levels, or if there is a better approach for adding this functionality.

Steps to reproduce

- Add an accordion using the uswds accordion button
- Open source and change the heading level to something other than h4
- Close source and note the heading was deleted

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes