The conditions editor widget needed to be updated to support dark mode,

because we use it outside of the admin UI for other things. This was all

pretty crusty, and while it was tempting to rewrite everything, I've

tried to keep my changes somewhat more minimal for now.
The display of the conditions now uses CSS grid in order to make the

table look more like a table. Widths of those grid columns are

determined by what happens to be visible in each row, instead of having

each row just flow individually with inline-block elements.
Colors use our ink datatable definitions, and icons have been switched

to use the tabler icons from ink instead of ugly colored fontawesome

icons.
As a bonus, I've made it so you can use the keyboard to select and

activate the delete-item entry. This change does not add full

accessibility for these controls, since I'm still trying to wrap my head

around the best practices for some of the things in there.
In order to fully enable a nice look, this also sets some basic styles

for <select> and <option> in configforms. These aren't very

style-able, but this makes it fit in much better.

Edited a bunch of conditions and saw that everything looked correct.
Manually injected the error element into the view and saw that it drew

  much nicer than before (errors are pretty hard to trigger--one needs

  to add an extension that adds condition choices or operators, and then

  disable that extension).
Used the keyboard to edit conditions.
Ran unit tests.
Ran js-tests