fix: add shadow dom support for portal provider (S2 v1.0.0, S1 v3.46.0)

[bsmiley1]

This PR attempts to expand Shadow DOM support by allowing portal components to be opened within a shadow root through the PortalProvider context api.

PDF for a more detailed description of the changes:
REACT_SPECTRUM_SHADOW_DOM_FIXES.pdf

✅ 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:

🧢 Your Project:

[snowystinger]

Thanks for the PR, I know you said some more things are coming including a detailed description of the changes. Can you include any references to existing/prior work?
https://github.com/adobe/react-spectrum/pulls?q=is%3Apr+is%3Aopen+shadow
#8806 <- it'd be great to include tests from here as well

I'm starting to refresh myself on all of this work now that our release and docs are out. A bit unfortunate that it's also time for the holiday shutdown, but I am spending some time on this topic this week and a little bit of next week.