Prior to this patch, we were unconditionally sticking all dependencies
in a "whole package' ElaboratedConfiguredPackage, which resulted in
cycles when there were internal dependencies on the library in question,
and broken deps with convenience libraries.  Happily, the fix is simple,
although I did have to add ConfiguredId to the "extra" dependency fields
to make it easier to tell if a dependency was external or internal.

I added an extra test to make sure that we give a good error message
if a package requires per-component builds (apparently, internal
libraries require per-component builds!)

Fixes #4388.

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>