fix: context provider values not memoized

[mohd-akram]

This prevents components being unnecessarily re-rendered.

✅ 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:

[devongovett]

Do you have an actual performance issue here? I'd rather not litter the code with memoization unless there is clear evidence of a perf issue that's actually caused by it.

[mohd-akram]

This is motivated by poor performance in Insomnia, which uses this library. Memoization of context values is IMO a correctness issue as much as it is a performance one (hence the lint). I will try to get some numbers. Is there any existing benchmark or demo that uses a large number of Spectrum components that I can use?