[BUG][Accessibility] Fix Tab index Size Swatches on Product Detail Page

[bendvc]

Description

There have been some changes with the swatch components. This resulted in some side effects on the product detail page where you could not select a "size" based on the swatch components not having a tab index. This happened because we weren't by default setting the tabIndex of the first swatch if there was no selection. This PR fixes this issue.

Types of Changes

• [x] Bug fix (non-breaking change that fixes an issue)
• [ ] New feature (non-breaking change that adds functionality)
• [ ] Documentation update
• [ ] Breaking change (could cause existing functionality to not work as expected)
• [ ] Other changes (non-breaking changes that does not fit any of the above)

Breaking changes include:

• Removing a public function or component or prop
• Adding a required argument to a function
• Changing the data type of a function parameter or return value
• Adding a new peer dependency to package.json

Changes

• Ensure first swatch is focusable when no swatch selection is available.

How to Test-Drive This PR

• Pull branch and run the template-retail-react-app
• Go to any PDP where there is a swatch for sizing.
• Tab through the PDP, specifically the product attributes and ensure you can focus the first size swatch.

Checklists

General

• [ ] Changes are covered by test cases
• [ ] CHANGELOG.md updated with a short description of changes (not required for documentation updates)

Accessibility Compliance

You must check off all items in one of the follow two lists:

• [ ] There are no changes to UI

or...

• [ ] Changes were tested with a Screen Reader (iOS VoiceOver or Android Talkback) and had no issues
• [ ] Changes comply with WCAG 2.0 guidelines levels A and AA
• [ ] Changes to common UI patterns and interactions comply with WAI-ARIA best practices

Localization

• [ ] Changes include a UI text update in the Retail React App (which requires translation)

[vcua-mobify]

I can tab and focus on the first size swatch but it took me a bit to realize that I should be using the left/right buttons to switch sizes rather than trying to tab to a different size 😅

[alexvuong]

Please add changlog for this PR.