Small accessibility fixes to toasts and combo box

[snide]

Summary

Easy one while I was cleaning out the backlog. As long as an item within a toast has focus, it will stick around. When you tab out, it will resume the countdown, similar to mouse actions.

Fixes #717

Also added a fixes #1343. Given how direct the combo box is with instruction it seemed like the best thing to do was announce the placeholder in the same way.

Checklist

• This was checked in mobile
• This was checked in IE11
• This was checked in dark mode
• Any props added have proper autodocs
• Documentation examples were added
• A changelog entry exists and is marked appropriately
• This was checked for breaking changes and labeled appropriately
• Jest tests were updated or added to match the most common scenarios
• This was checked against keyboard-only and screenreader scenarios
• This required updates to Framer X components

[cchaos]

Should the toast also still persist if the user has clicked inside it, example is selecting text:

[snide]

This is ready for a final review I think. I don't know how to address the text selection stuff, but between the mouse hover and the tabbing inside I think it's good enough to close out that old ticket.