Checkbox / Radio Button: Improve HTML whitespace sensitivity - #239

The expectation is that there should be no user-facing visual effect of these changes, hopefully demonstrated by a passing visual regression test.

I lied... the horizontal offset of the checkboxes changes ever-so-slightly. Checking out the artifacts for the build (specifically -diff.png) gives a good overview of the changes. I might be able to get this back to its original styling, but in retrospect I feel this is a bit more faithful to the original Figma designs, as far as the checkboxes and radios appearing at the leftmost edge, with a consistent right margin of 0.5rem. It gives a slightly imbalanced appearance in the bordered and tile variations, but this exists in the Figma design as well. Curious @nickttng @anniehirshman-gsa @cdelivuk if you'd have thoughts here.

Live demo: https://federalist-2f194a10-945e-4413-be01-46ca6dae5358.app.cloud.gov/preview/18f/identity-style-guide/aduth-tile-checkbox-label-size/components/form-fields/#radio-buttons

Noting that the upstream uswds/uswds#4286 is now merged, we'll need to come back and revisit this in the future to reconcile redundancies.