fix: Ensure that opening a submenu via enter/space moves focus to first item in submenu

[LFDanLu]

Closes #9686

✅ Pull Request Checklist:

• Included link to corresponding React Spectrum GitHub Issue.
• Added/updated unit tests and storybook for this change (for new code or code which already has tests).
• Filled out test instructions.
• Updated documentation (if it already exists for this component).
• Looked at the Accessibility Practices for this feature - Aria Practices

📝 Test Instructions:

Go to RAC Submenu story and make sure that Enter/Space opens the submenu and that focus lands on the first item in the submenu. Pressing Enter/Space again should trigger the submenu item

🧢 Your Project:

RSP

[LFDanLu]

tried writing a test for this but it passes without the change since the timing isn't quite the same as in browser. Will be worth writing one in chromatic using the actions or via the real browser test PR when that goes in

[rspbot]

Build successful! 🎉

• View the storybook
• View the S2 storybook
• View the S2 docs
• View the React Aria docs

[nwidynski]

Suggested change

	// click above sets modality to "virutal", need to set interaction modality back to 'keyboard' so focusSafely calls properly move focus
	// click above sets modality to "virtual", need to set interaction modality back to 'keyboard' so focusSafely calls properly move focus

[nwidynski]

Suggested change

	// click above sets modality to "virutal", need to set interaction modality back to 'keyboard' so focusSafely calls properly move focus
	// to the newly opened submenu's first item.
	// click above sets modality to "virtual", need to set interaction modality back to 'keyboard' so focusSafely calls properly move focus
	// to the newly opened submenu's first item.