Remove htmx functionality

[aloftus23]

🗣 Description

HTMX is no longer needed.

💭 Motivation and context

No longer in use and presents potential vulnerabilities.

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✅ Pre-approval checklist

• [x] This PR has an informative and human-readable title.
• [x] Changes are limited to a single goal - eschew scope creep!
• [x] All future TODOs are captured in issues, which are referenced in code comments.
• [x] All relevant type-of-change labels have been added.
• [x] I have read the CONTRIBUTING document.
• [x] These code changes follow cisagov code standards.
• [x] All relevant repo and/or project documentation has been updated to reflect the changes in this PR.
• [x] Tests have been added and/or modified to cover the changes in this PR.
• [x] All new and existing tests pass.

[coveralls]

coverage: 26.288%. remained the same when pulling 2ba173138c33bf9ce09d4d2b627965a1aa8de581 on AL-fix-htmlx-vuln into 14755187fbf5fb4af7c447c5cdd8b6cfdd4de576 on develop.

[aloftus23]

@dav3r @jsf9k This is ready for review.