Add -blackbox option to setundef pass

[KrystalDelusion]

What are the reasons/motivation for this change?
From Dev JF:

Add an option -blackbox to setundef which will operate on the non-blackbox modules and remove the instances (cells) of blackbox modules and connect their outputs to $anyseq cells instead. Make this the default in SBY. This way we avoid any problems with needing to derive de-blackboxed modules to handle I/O signals with parametrizable widths, which isn't possible when they came from verific.

Explain how this is achieved.

• Add -blackbox option to setundef. If used, all instances of blackboxes in a module will be removed via cutpoint -undef. The undef wires can then be handled as usual by setundef. e.g. setundef -blackbox -anyseq will remove instances of blackboxes and replace their outputs with $anyseq cells.
• Add test for setundef -blackbox.
• Add $scopeinfo cells for removed instances (should this be in cutpoint or in setundef?)

If applicable, please suggest to reviewers how they can test the change.