Module groups to support variants

A future patch will rewrite context and module_ctx to support multiple
variants of a single module.  This requires adding a layer of indirection
between the module defined in a Blueprint file and the Module object
built by the build logic.

What used to be called a moduleInfo struct is now a moduleGroup struct,
and contains the generic information taken from the Blueprint file.
Inside the moduleGroup struct is a list of moduleInfo structs, which
contain a logicModule pointer to the Module object returned by the
ModuleFactory function from the build logic.  moduleInfo also contains
the name of the variant, as well as the dependencies after they have
been resolved from Blueprint string dependencies to dependencies on
a specific Module.

Change-Id: Id4d516ffc13381c3ce07b80eaf32d9090ae43703