[Gemfile] Add option to cp_gem to make using gem from path easier

[Gemspec] Bump Molinillo to `~> 0.4.2`

[Command Project] xcodeproj was renamed to project

[Podfile] Adopt renaming from xcodeproj to project

[SpecsState] Ensure only root names are stored

[XCConfig] Don't recurse for transitive dependencies

[Validator] Only import if the pod target is being built

[PodTargetInstaller] Fix #4819

Neither PROJECT_HEADERS_FOLDER_PATH exists nor it makes sense to bundle project headers into the built framework, so skip them here.

and in that way project headers implicitly

[Analyzer] Fix #4751