WIP Drop Premake

[expipiplus1]

TODO:

• Replace the release action workflows
• Falcor tests
• Test as a submodule
• Archive slang-glslang and slang-llvm repos
• Remove premake generated files and the cmake code to clean them
• Update build instructions
• Document CI setup for CMake

[csyonghe]

We need to update the build instructions document along with this change.

[jkwak-work]

Our contribution guide needs to be modified as well. https://github.com/jkwak-work/slang/blob/master/CONTRIBUTION.md#build-slang-from-source

[csyonghe]

Before we can remove premake, our gitlab CI also need to be updated first to use cmake.

[kaizhangNV]

looks like nothing change on : release-*.yml files. How is that going to work? Because those workflows also use premake to build the release binary?