Support and test amsmath macros `\varGamma...\varOmega`

[wspr]

Description

amsmath doesn't use \upGamma but rather \varGamma.

Check/indicate

• [x] Relevant for XeTeX
• [x] Relevant for LuaTeX
• [x] Issue tracker has been searched for similar issues?
• [x] Links to discussion if appropriate:
  • https://tex.stackexchange.com/questions/105653/emulating-amsmaths-vargamma-varomega-with-unicode-math

Minimal example demonstrating the issue

\documentclass{article}
\usepackage{unicode-math}
\begin{document}
$\varGamma$?
\end{document}

Further details

These commands do appear to work when amsmath is loaded, so it might just be a matter of ensuring and checking the behaviour makes sense.