Qt Creator: Build and test on Windows ARM64

Qt Creator ships for Windows on ARM64, but nothing built it there
before integration, so code that does not compile with MSVC for
ARM64 was only found after it was merged.

This needs qt-creator's instructions to provision Windows ARM64
machines (qt-creator/qt-creator change 779407) on every branch that
COIN builds.

Assisted-by: Claude Code
Change-Id: Iec61be8417f1fab5fa401897e7c8c2a31fe4b6da
Reviewed-by: Eike Ziller <eike.ziller@qt.io>