Solver can automatically suggest changes when there is an unresolvable conflict

[harendra-kumar]

See #1583 (comment).

We can automatically determine the minimal number of user packages to remove to be able to come up with a workable build plan. We can do this automatically when init/solver is used with --force and write the removed packages commented out in the config with an appropriate conflict reason comment. This allow diagnosing and fixing dependency problems quickly.

This will perhaps depend on #1615 .

[mgsloan]

Makes sense! #1593 is also relevant, as otherwise you can't really select just the cabal files that are needed. Might be good to provide the commandline options along with the suggestion.