Revert "Extract `buildFolderURL.URLByAppendingPathComponent`… into func."

This reverts commit 5900120794b36c597efad2ccfa94730997e22095.
Revert "Test for `.Success` and `.Failure` of `otool` in `XcodeSpec`."

This reverts commit 366905e102d2a433a8a789754be3f1f313e3c089.
Split `output` into `otoolResult` and `output`.
This allows us to test `otoolResult.error()`.