fix(color-contrast): greatly improve color-contrast-matches speed. add aria/get-accessible-ref

[straker]

The color-contrast-matches function would try to query the entire DOM for every node with an id attribute, and all children of that node would also do the same check. This caused the matcher to take ~40s on a relatively small page with lots of IDs. Since we were already caching id references in aria/is-accessible-ref, I was able to leverage that same code to create a new function that returns an array of all id ref DOM nodes. That way we could just reference that cache in color-contrast-matches and reduce the time to about 1 second.

Here are the perf results in running only the color-contrast rule on https://www.chase.com/content/dam/chaseonline/en/demos/cbo/launch.html.

Time Before (ms)	Time After (ms)
42947.73	1271.18

NOTE: We are in a code freeze so cannot merge this until after 4.1 is released on Monday.

Closes issue: #2479

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[WilcoFiers]

Looks good. I think there are a lot more places in axe-core that now we have a cache of ID references we could speed up. Probably best to open a tech debt issue for that one instead of pile it onto this PR. Here's a list though:

• checks
  • aria-required-parent-evaluate
  • explicit-evaluate
  • hidden-explicit-label-evaluate
  • multiple-labels
  • duplicate-id-evaluate
• matches
  • duplicate-id-active-matches
  • duplicate-id-misc-matches
  • scrollable-region-focusable-matches
• commons
  • text.labelVirtual
  • dom.findElmsInContext
  • dom.isVisible (usemap lookup)

To make that easier, we can probably simplify by having something like a idrefsReverse function, that takes a node (with an ID) and an attribute and looks up any element references the ID with that attribute. I'll leave it up to you if you want to do that in this PR or another.

const virtualControls = idrefsReverse(ancestorNode, 'aria-labelledby')
	.map(control => getNodeFromTree(control));