fix: correct focus-ring on Textarea when resized

[lazd]

Description

Fixes the misalignment of focus-ring when resizing Textarea. Fixes #1383

Side effect: width of textarea must be set on the input now, not the outer element.

How and where has this been tested?

• How this was tested: i resize, i focus, i smile
• Browser(s) and OS(s) this was tested with: Chrome

Screenshots

To-do list

• [ ] Verify approach with @Westbrook
• [ ] This pull request is ready to merge.

[lazd]

@Westbrook this should do it. We're using the :after pseudo-element to draw the focus-ring to nicely support quiet. If it's unacceptable to set size on the input itself (instead of the outer element), we can look into retooling this to put a box-shadow on the input.

[pfulton]

We've got a new PR in for migrating TextArea to the new tokens system, which should account for this, but also noting that SWC has a workaround for this currently here.