Add LunarG demo app repository as a submodule.
Add LunarG demo config to makeAll script.
Rename Demos/README_MoltenVK_Demos.md to Demos/README.md.
Do not copy Demos folder to MoltenVK runtime distribution.
Do not copy ThirdPartyConfig.md to MoltenVK runtime distribution.
Add cmake as a dependency in README.md.