Add Windows ARM64 MSVC CI jobs

This PR adds Windows ARM64 coverage to CI using GitHub's windows-11-arm hosted runner.

Changes

• Four new matrix entries that mirror the existing Windows x64 MSVC jobs:
  • Windows ARM64 MSVC 2022 Debug (C++17) / ASAN
  • Windows ARM64 MSVC 2022 Release (C++17)
  • Windows ARM64 MSVC 2022 Debug (C++20) / ASAN
  • Windows ARM64 MSVC 2022 Release (C++20)
• ilammy/msvc-dev-cmd now takes arch from the matrix (${{ matrix.config.arch || 'x64' }}), so the existing x64 jobs are unchanged.
• The Setup CMake step is skipped on ARM64 because CMake 3.16.2 has no Windows ARM64 binaries. Those jobs use the CMake that comes preinstalled on the runner.