Add instance Binary LocalBuildInfo
Use Binary instance to save/restore dist/setup-config
Load binary LocalBuildInfo in package-tests

PackageTests has its own version of getPersistBuildConfig which does not
check which version of Cabal created dist/setup-config. Now that the
LocalBuildInfo is written with Binary, this version needed to be
updated, too.
Clarify Cabal dependencies policy

[ci-skip]
Merge pull request #2076 from ttuegel/binary-lbi

Use Binary to save/restore persistent build config