CI for build whisper.cpp libraries

[Macoron]

Added new Github Action for building native C++ libraries of whisper.cpp. It can be run manually by creating your fork and going into Actions => Build C++ => Run workflow. After pipeline completed, download compiled libraries in artifacts tab.

You can choose different whisper.cpp repo and tag/branch that you want to build. By default it's using ggerganov/whisper.cpp and v1.2.1 tag.

Some remarks for each platform:

• Windows x86_64 - works great, compiled by msbuild
• Linux x86_64 - compiled in Ubuntu 18.04 docker. This should work on Ubuntu 18.04 and newer
• MacOS - ARM build works great, but x86_64 build crashes. I suspect there is a bug in original cmake. Should be fixed by new version of whisper.cpp
• iOS Device/Simulator - works great, no changes
• Android ARM64 - works, but need very specific version of NDK. Others fail to compile in Unity.

Except MacOS x86_64 all binaries compiled correctly and work on my machines.

Fun Fact: gcc build for Ubuntu works up to 20% faster than Windows msbuild on same hardware.