fix(core): slotController isEmpty respects text nodes

[bennypowers]

What I did

1. make slotcontroller's hasContent/isEmpty consider text nodes

Testing Instructions

1. patch contents into RHDS, and check that cards with text nodes in default slot but no wrapping element still display their contents

Notes to Reviewers

1. see https://stackblitz.com/edit/stackblitz-starters-u2qbnw?file=index.html

[changeset-bot]

🦋 Changeset detected

Latest commit: e5103c5

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

This PR includes changesets to release 1 package

Name	Type
@patternfly/pfe-core	Patch

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[github-actions]

✅ Commitlint tests passed!

More Info

{
  "valid": true,
  "errors": [],
  "warnings": [],
  "input": "fix(core): slotController isEmpty respects text nodes"
}

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[github-actions]

SSR Test Run for f220b8f: Report

[adamjohnson]

Letters get thoroughly matched 👍