fix: Allowing BC era timestamps in fromAbsolute (#6541)

[KimPeeters]

Closes #6541

✅ 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:

The unit test should cover this. By hand:

import { fromAbsolute } from "@internationalized/date";

console.log(fromAbsolute(-62135596800001, "UTC").toAbsoluteString());
// ^^ should return:  0000-12-31T23:59:59.999Z

[snowystinger]

Thanks for your patience, will get other reviews