Prebiult libyuv.xcframework for iOS, macOS, Mac Catalyst and tvOS

Use as a dependency in C code with #include <libyuv.h>, or import as a Swift module with import Clibyuv.

• Built with Chromium’s GN/Ninja toolchain
• NEON optimizations are enabled for arm64 (libyuv_use_neon=true)
• ASM optimizations are enabled for x86 (SSSE3/AVX/AVX2 etc.)
• JPEG is disabled on all platforms