Have VTK-m eat its own dog food when it comes to its configuration. Load
the same configuration for building VTK-m as would be loaded (more or
less) when using find_package(VTKm) in an external project.
This includes adding lots more components to the packages so that all the
setup (e.g. OpenGL, TBB, etc.) can be set up correctly. It is also a
significant change to how these components are declared. The component
configuration is simplified a bit and unified in a single file.
These asserts are consolidated into the unified Assert.h. Also made some
minor edits to add asserts where appropriate and a little bit of
reconfiguring as found.
