Clean out AArch32 (ARMv7) ARM32 code paths #309

Officially the Window SDK starting with 26100 no longer includes ARM32 libraries. Building ARM32 requires using 22621. VS 2022 still supports building for arm with a cross-platform x64_arm and arm64_arm, but this is deprecated in VS 2026.

The majority of the DirectXMath ARM-NEON codepaths were written for ARM32 and are portable to ARM64, with a few specific ARM64 optimizations sprinkled in. I should be able to refactor the library a bit to drop ARM32 support and clean it up a little.

https://learn.microsoft.com/en-us/windows/arm/arm32-to-arm64