Support passing React.ReactElements for icons

[camertron]

Closes https://github.com/github/primer/issues/3907

We accept React.FunctionComponent for a number of icon slots, but not a regular 'ol React.ReactElement. This PR updates several components to accept both, which should make Figma happier.

Changelog

New

Changed

Updated the following components to accept a React.ReactElement for icon slots:

• AutocompleteMenuItem
• AutocompleteMenu
• SegmentedControlButton
• SegmentedControlIconButton

Removed

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

This PR should not require any updates in production, as it is purely additive.

Merge checklist

• Changes are SSR compatible
• (GitHub staff only) Integration tests pass at github/github (Learn more about how to run integration tests)

[changeset-bot]

🦋 Changeset detected

Latest commit: 8a0777a

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]

size-limit report 📦

Path	Size
packages/react/dist/browser.esm.js	96.95 KB (+0.02% 🔺)
packages/react/dist/browser.umd.js	97.34 KB (+0.07% 🔺)

[joshblack]

Looks great! If you have the time, it'd also be great to:

• Update stories to use the React.ReactElement format (this will be preferred over React.FC moving forward)
• Add a test either as a type test or in Jest for the new type

[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!

[camertron]

Hey @joshblack 👋 I added type tests, but I wasn't able to find any instances of our stories passing anything for visuals/icons other than React.ReactElements. That's probably because my React fu isn't as attuned as yours. Are there any specific examples you're thinking of?