These integration tests, unlike the existing ones, don't call cabal as
an external processes. Instead they use the cabal code directly. This
makes it possible to conveniently test catching exceptions.

Add a couple tests for exceptions in finding projects. There should be a
lot more for the various phases of planning.

Also add a couple tests for exceptions in the configure and build
phases. These test the previous patch that improves the exception
handling so that failures are added into the residual plan rather than
just propagating immediately.