Handle options not registered on module import

Try to discover and include options that are not registered on module import but
when actually executing the code.

We find calls to register_opts() that cannot be handled on import, extract the
arguments and explicitly call register_opt() to make oslo.config aware of them.

Change-Id: I4566b68b59d5a7a1e15cbd3fb9fcec1a51f9abac
Merge "Handle options not registered on module import"