[minor] Popover autoFocus events to manage focus on trigger

[Jialecl]

Checklist
(Check off all the items before submitting)

• Build process is done without errors. All tests pass in the /lib directory.
• Self-reviewed the code before submitting.
• Meets accessibility standards.
• Added/updated documentation to /website as needed.
• Added/updated tests as needed.

Purpose
Added focus events that trigger when popover is opened or closed