Vulkan builds for Intel Macs

[mrglutton]

Hello maintainers!

Would you consider adding official precompiled binaries with Vulkan support for Intel-based macOS machines (using MoltenVK)?

There is a large number of users on macs that use Intel Macs with AMD GPUs that without compiling llama.cpp manually are sentenced to use rather slow CPU mode.

Most of Macs have rather powerful GPUs, and users can't use them for LLMs without compiling directly (most can't do it due to lack of experience with compiling and few guides online are full of errors).