fix(accordion): fixing header tag, fixing heading text attribute

[brianferry]

What I did

1. Added an anonymous slot checker in the pf-accordion-header component.

• This checks for whether an anonymous slot has been passed in for the header
  • DOES NOT have an anonymous slot = we add the header tag to the shadow dom
  • DOES have an anonymous slot = we DO NOT add the header tag to the shadow dom

2. We have / had an issue with the heading-text attribute not showing correctly in the header, this has been fixed
3. Adding a demo to show the attributes being used instead of the anonymous slot

Testing Instructions

1. DP
2. Open the developer console and inspect the accordion demos
3. Verify that the accordion headers with slotted in content do not have nested header tags in the shadow dom
4. Verify that the accrdion headers in the demo that have text / tags passed in via attributes have the nested header tags in the shadow dom.
5. Verify that the text passed in through heading-text is showing in the header as expected

[changeset-bot]

🦋 Changeset detected

Latest commit: 62750ec

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@patternfly/elements	Patch

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