Components: update ColorPicker unit tests

[chad1008]

What?

Updates ColorPicker's unit tests to provide more meaningful feedback, and replace fireEvent with userEvent.

Why?

The existing tests attempted to manipulate the two-dimensional color picker, and would check to see if onChange was fired with a hex or a hex8.

While attempting to migrate these tests from fireEvent to userEvent I found that while they might fire with the right format, it was never actually the correct color. It was always #000000, optionally with two more digits for the alpha value. Chatting with @ciampo and @jsnajdr revealed that this is due to JSDOM not rendering layout, so moving slider handle between coordinates isn't actually possible.

If I recall correctly, this led to a fun bug where trying to slide a slider resulted in effectively toggling it between 0 and infinity... strangeness ensued and long story longer, the existing tests weren't actually functioning as they appeared to be.

The new/updated tests aim to focus on the inputs our unit tests can get accurate data from.

How?

The individual inputs for hex, rgb, and hsl inputs are all tested independently. The existing test for legacy props (which uses a different internal format for color values and different callback when the value changes) has been updated as well.

I had initially hoped to also test the inputs as a group (e.g. updating all three rgb values and confirming the correct color was called) but this didn't prove possible. When updating the second or third value, the previous value(s) always reset to zero. I suspect this is happening due to the physical slider being updated to match the value entered by the test, which fails because of the no-layout issue I've described above.

Followup

I'd like to add another test for the Copy button, but I wasn't quite sure how to properly mock it. Rather than delay this PR, I'll put this on a list to come back to later.

Testing Instructions

Confirm unit tests pass

[jsnajdr]

I have one more suggestion for improving a color picker query. Otherwise this looks good 👍 Thanks for addressing all feedback.