Refactor plugin installation
This is a decent refactor to allow the cmb-superbuild to be extended so that other CMB-based apps can reuse the infrastructure. Now, plugins can be listed before including cmb.bundle.common
to be scanned for information and then all of that collated information is used in the platform-specific scripts to handle plugins.
This will require testing of the generated binaries on each platform to make sure they still work as intended.
Cc: @aron.helser