Fix keyboard focus for tooltip group headers

[smbea]

Describe the Bug

I order to fix #266, we move the tooltip to outside the group header containing position: sticky. This made it so the tooltip content isn't reachable in the keyboard focus tree: links can't be focused, for example.

Steps to Reproduce

1. use keyboard to focus group label
2. 'tab' again and see that it skips the tooltip selectable content

Expected Behavior

Tooltip content should be reachable via focus tree.

Environment

• Host (Browser/Node version), if applicable: [e.g. MS Edge 18, Chrome 69, Node 10 LTS]
• OS: [e.g. Windows 7]
• Library version: [e.g. 2.0.0]