feat(rux-accordion-item) add part to the content wrapper

[kiley-mitti]

Brief Description

added part=content to the span that wraps the details slot. It has some padding on it and that can't be manipulated without the part.

JIRA Link

Astro-6233

Related Issue

General Notes

Motivation and Context

Allows people to remove padding from the content slot wrapper if they need to.

Issues and Limitations

Types of changes

• [ ] Bug fix
• [x] New feature
• [ ] Breaking change

Checklist

• [ ] This PR adds or removes a Storybook story.
• [ ] I have added tests to cover my changes.
• [x] Regressions are passing and/or failures are documented
• [x] Changes have been checked in evergreen browsers

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🦋 Changeset detected

Latest commit: 581691aa3280b25fb0bb901e1b52be785b5e73dc

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

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