[BUG] Dependency Warnings

[ryanmrichard]

Describe the bug
This is low priority, but when I build NWChemEx I see warnings from compiling dependencies.

To Reproduce
Build NWChemEx and look at the build output.

Expected behavior
Traditionally warnings for dependencies are suppressed in build logs, since it's not the current project's fault the dependency doesn't compile cleanly.

Additional context
IIRC CMake automatically suppresses warnings for dependencies if they are marked as private dependencies. It may be the case that we need to introduce a PRIVATE_DEPENDS key for cmaize_add_library in order to distinguish between public/private dependencies.