Export CMake Targets better

There are a lot of duplication in the exported config files in Smith that can be removed and leveraged fully from Serac. For example, we should just be using the MFEM target created/imported from Serac inside of Smith, instead of recreating it.

Start by locating Smith's exported CMake configuration files and the corresponding Serac target setup, then compare how the MFEM target is created or imported in each project. Done means Smith reuses Serac's MFEM target and removes duplicated target configuration without breaking its exported package configuration.

Written by the indexing model from the issue text.