CSS:Selector: Align with 3.x, remove the outer `selector.js` wrapper

CSS:Selector: Align with 3.x, remove the outer `selector.js` wrapper

Bring some changes from `3.x-stable`:
* rename `rtrim` to `rtrimCSS` to distinguish from the previous `rtrim`
  regex used for `jQuery.trim`
* backport one `id` selector test that avoids the selector engine path

Other changes:
* remove the inner function wrapper from `selector.js` by renaming
  the imported `document.js` value
* use `jQuery.error` in `selectorError`
* make Selector tests pass in all-modules runs by fixing a sinon mistake
  in Core tests - Core tests had a spy set up for `jQuery.error` that wasn't
  cleaned up, influencing Selector tests when all were run together

Closes gh-5295