feat(Popover): Convert Popover to CSS modules behind team feature flag

[francinelucca]

Closes https://github.com/github/primer/issues/4139

Changelog

New

• Popover dev story to test sx and style props with VRT
• Popover module css
• Snapshots for new dev story

Changed

• Refactor Popover e2e tests and add new dev story
• Refactor Popover to use CSS modules when team feature flag is turned on

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; if selected, include a brief description as to why

Testing & Reviewing

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github (Learn more about how to run integration tests)

[changeset-bot]

🦋 Changeset detected

Latest commit: 3cdcda9

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

This PR includes changesets to release 1 package

Name	Type
@primer/react	Minor

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[github-actions]

👋 Hi, this pull request contains changes to the source code that github/github depends on. If you are GitHub staff, we recommend testing these changes with github/github using the integration workflow. Thanks!

[github-actions]

size-limit report 📦

Path	Size
packages/react/dist/browser.esm.js	100.25 KB (+0.22% 🔺)
packages/react/dist/browser.umd.js	100.53 KB (+0.18% 🔺)

[primer-integration]

👋 Hi from github/github! Your integration PR is ready: https://github.com/github/github/pull/351364

[primer-integration]

🟢 golden-jobs completed with status success.

[jonrohan]

Awesome ✨

[github-actions]

👋 Hi, there are new commits since the last successful integration test. We recommend running the integration workflow once more, unless you are sure the new changes do not affect github/github. Thanks!

[github-actions]

👋 Hi, there are new commits since the last successful integration test. We recommend running the integration workflow once more, unless you are sure the new changes do not affect github/github. Thanks!