Add Windows ARM64 support in CI

[Harishmcw]

This PR adds Windows ARM64 support to the MSBuild and CMake CI workflows.

Changes:

• CMake
  • Added Windows-MSVC-ARM64 and Windows-MinGW-ARM64 jobs.
  • Configured appropriate vcpkg triplets and generators.
  • Added conditional -A handling for MSVC ARM64 builds.
• MSBuild
  • Added ARM64 platform configuration to portaudio.vcproj and portaudio.sln
  • Added ARM64 to the CI build matrix.

[RossBencina]

To check that this wasn't going to create backward compatibility problems I opened the .sln solution in Visual Studio 2005. There were no obvious problems introduced by the presence of the ARM64 configuration (it would not build of course). The Win32 target seemed to build (modulo some unrelated errors that we should probably fix).

Could I get you to fix one more thing please? : When I opened the solution ARM64 was already the selected configuration. Could you make open with the 64-bit intel config please?

[Harishmcw]

Hi @RossBencina,

After some investigation I found that on Visual Studio 2005, the default configuration is picked alphabetically, since ARM64 sorts before x64, it ends up selected by default.