Allow initial focus to be provided to confirm prompt

[acelaya]

This PR extends the options for confirm, including one to allow defining which of the two buttons should be initially focused.

By default it keeps focusing the "cancel" button, as that's probably the non-destructive option in most of the cases.

[acelaya]

I'm checking the failing test. I have reproduced it locally by running it a couple of times, so I'm looking for a different way to test this.

EDIT: Seems like waitFor checking that the active element is not the body does not always resolve in 10ms. I can increase the timeout, but I'm not completely sure if that's a microtask or a macrotask, and therefore, if it will make a difference or just continue failing with the same cadence, just taking longer to do it.

EDIT 2: I found what I think is a more consistent way to wait for the button to be focused by adding a focus event listener to it.

const waitForButtonToFocus = () =>
  new Promise(resolve => getButton().addEventListener('focus', resolve));
await waitForButtonToFocus();

assert.equal(document.activeElement, getButton());

[codecov]

Codecov Report

Merging #1224 (f6daf66) into main (570068e) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main     #1224   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           59        59           
  Lines          829       832    +3     
  Branches       316       318    +2     
=========================================
+ Hits           829       832    +3     

Files Changed	Coverage Δ
src/util/prompts.tsx	100.00% <100.00%> (ø)

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[robertknight]

EDIT 2: I found what I think is a more consistent way to wait for the button to be focused by adding a focus event listener to it.

If there is a specific event that you can wait for rather than a timeout, that is almost always preferable.

[robertknight]

LGTM