Teach BundleUtilities and GetPrerequisites how to fixup bundle using @rpath.

The following functions and variables have been introduced:

  IS_RESOLVED_ITEM_EMBEDDED
  BU_RESOLVE_ITEM_RPATH_DIRS_OVERRIDE
  GP_RESOLVE_ITEM_RPATH_DIRS

In function "set_bundle_key_values", use the function "gp_resolve_item" to
resolve the emdedded_item. Before this commit, the function was able to
resolve only item matching "@executable_path"

Since commit c2895f48a, library belonging to the project are expected
to be copied or installed within the bundle.