Add cli target support for out-of-project package names

There is nothing except for syntax support, but this is a first step
towards proper support for targets refering to dependencies or to out of
project packages.

For the moment, when used, it will report:

    cabal: Cannot build the package foobar, it is not in this project
    (either directly or indirectly). If you want to add it to the
    project then edit the cabal.project file.

Also update the test output for an integration test.