Analysis and dev: update/replace popper.js

Summary: Replace popper.js v1 with something that is actively maintained.

Details: popper.js v1 generates a console warning on install:

You can find the new Popper v2 at @popperjs/core, this package is dedicated to the legacy v1

v1 has been unmaintained for nearly three years. v2 is occasionally maintained; the current incarnation has been rebranded as Floating UI. There are migration guides for both v1->v2 and v2->Floating UI.

Stripes-components uses Popper through its own 'Popper' primitive. A migration path that incurs as little effort on the part of ui-module code should be prescribed.

If the development lift of this is too heavy, we can create another story for work beyond analysis.