Refactor to use Popover API

[cubap]

Browser support covers all our cases for Modals, Toasts, and Tooltips with the Popover API. We should simplify our use of these to act as dialog, popover, tooltip and toasts. We do not need to remove our custom elements or events completely, but use the existing architecture with the simplified handling to reduce the weight of the javascript handling and improve cross-browser support.

[cubap]

Dialog has a separate API from Popover but it is similar. Choosing dialog means instead of simple dismissal, the user must interact with what pops in to continue.