WIP: playing around with floating UI

[ktuite]

Closes #1084

Jan 16 update

• hover cards work
• QR codes work on app user page and draft testing page
• QR code can be switched between managed and legacy

Approach:

• I'm currently kind of mimicking the old popover behavior, except instead of copying the popover content into a new popover element, i'm just moving the original element onto the screen and then back off.

Questions:

• There's probably something I could do differently... maybe instead of moving it, i could hide/show the popover in a way that wasn't possible before?
• Since I no longer introduce a new .popover element, i just have the original .popover-content-source, and I changed a couple tests or event handlers to refer to that. I feel like it should have a different class name for this approach, though. Just renaming the top level div class .popover didn't work but I'm not sure why.
• Related to the point above, the classes that check for the existence/non-existence of a particular element dont make sense anymore.
• I had been playing with arrow styling and other kinds of style earlier but I don't currently have any arrows or fancy styling e.g. drop shadows.
• Popover (and maybe even that fieldKeyQrPanel component) could be updated to use composition API

What has been done to verify that this works as intended?

Why is this the best possible solution? Were any other approaches considered?

How does this change affect users? Describe intentional changes to behavior and behavior that could have accidentally been affected by code changes. In other words, what are the regression risks?

Does this change require updates to user documentation? If so, please file an issue here and include the link below.

Before submitting this PR, please make sure you have:

• run npm run test and npm run lint and confirmed all checks still pass OR confirm CircleCI build passes
• verified that any code or assets from external sources are properly credited in comments or that everything is internally sourced