Rethink colors/formatting for JavaScript Code Hint list items

[joelrbrandt]

@njx @GarthDB @iwehrman We haven't yet done any XD work on how the different "types" of items in the JS Code Hint list are formatted.

@GarthDB did an initial review of the current implementation and didn't see any problems with merging it as is. But, he felt that we should re-consider it when we have time.

We decided to track this with a bug, initially assigned to @njx, who will try to make progress on it opportunistically.

[pthiess]

Reviewed, eventually a MTB.

[iwehrman]

As a result of #3490 from @larz0, I propose that we consider this fixed. Improvements could still be made, but I don't think that wish should be tracked as an open-ended bug. Marking FBNC for @njx to close.

[larz0]

There's a separate issue for code hint improvement that I haven't got around to yet, see #3622.

[njx]

I have one specific issue left, but will open a new bug for it. Closing.