Fix overlay positioning when portal container is not body

[devongovett]

Fixes popover positioning with contextual help trigger, and left/right placement.

[rspbot]

Build successful! 🎉

• View the storybook
• View the storybook-17
• View the storybook-16
• View the documentation

[rspbot]

## API Changes

unknown top level export { type: 'identifier', name: 'Column' }
unknown top level export { type: 'identifier', name: 'Column' }
unknown type { type: 'link' }
unknown type { type: 'link' }
unknown type { type: 'link' }
unknown type { type: 'link' }
unknown type { type: 'link' }
unknown type { type: 'link' }

[reidbarber]

LGTM, tested usePopover and Menu Item unavailable in docs and storybook

[LFDanLu]

Tested docs popovers for RSP, React Aria, and RAC LGTM. Storybook stories look good at various offsets/placement options as well. Chromatic ran clean as well