Previously we would avoid adding this since it has
an invalid module name, but we can follow the same
logic as the driver and set the module name to
`main`.
Only consider `.o` and `.swiftmodule` inputs for now. Previously
we could end up with unnecessary dependencies for e.g plugin
dylibs, but we don't build and patch those in currently.
This is a tool specifically designed to generate
Xcode projects for the Swift repo (as well as a
couple of adjacent repos such as LLVM and Clang).
It aims to provide a much more user-friendly experience
than the CMake Xcode generation (`build-script --xcode`).
