R&D: How to use CMake as project generator

[ekharkunov]

Questions:

1. Can we use CMake as project generator for the native toolchain (all platforms)?
2. Does CMake support Cocoapods and Swift package manager dependencies file?
3. What kind of software need to be installed to build generated project?
4. How to control CMake options during project generation (based on current App manifests)? How to control which options are allowed, which are not.
5. What changes should be done in extensions to be able to use with generated project?
6. Plan for migration from old build pipeline to new one
7. Backward compatibility (old projects should be built)