Fix for local packages in nested xcode groups

[TomaszLizer]

I have stumbled on issue where dependency-graph was not working for my project.
Afgter debugging in turned out that there were two main reasons:

• Xcode project structure with local package (XCLocalSwiftPackageReference)
  Causing Error: The element XCLocalSwiftPackageReference is not supported. or zsh: segmentation fault dependency-graph TestDependency.xcodeproj #25 when running from console
  This is fixed by bumping XcodeProj to version that supports XCLocalSwiftPackageReference
• Local Package in prject structure which is nested in group. Since each group shares its own path, then path of package in such group as it was created previously did not accomodated for skipped path components of other groups.
  Eg PackageB which resides in group NestedPackages was recognized other be in <root>/PackageB instead of root/NestedGroup/PackageB.
  This is fixed by utlising fullPath from XcodeProj.

Some other issues might be related to this fix as well, eg:

• Fails to locate local swift packages #24

Updated tests to reflect those changes - since bug was in live path validation of XcodeProjectParserLive -> I have added FileSystemLive to two tests to take that part into account.
Additionally I have updated main example prioject as well as its copy to reflect those changes in tests.