Support generation of xcodeproj file

Helping links:
* https://github.com/CocoaPods/Xcodeproj
* https://github.com/tuist/XcodeProj
* http://www.monobjc.net/xcode-project-file-format.html
* https://crates.io/crates/cargo-xcode
* https://github.com/fstephany/xcodeproj-rs
* https://github.com/kronenthaler/mod-pbxproj
* https://github.com/Karumi/Kin
* https://github.com/CocoaPods/Xcodeproj
* https://github.com/yonaskolb/XcodeGen

See also:
* https://github.com/chinedufn/swift-bridge
* https://github.com/nvzqz/swift-bindgen