add SDC file type to radiant

[johnathan-convertino-afrl]

SDC files are supported and allow for multiple constraint files vs only one with PDC.

[olofk]

Thanks. Could you also update the reference files accordingly so that the test suite passes? Some more info about testing and using the GOLDEN_RUN env var to update files automatically can be found here https://edalize.readthedocs.io/en/latest/dev/tests.html#testcases

[johnathan-convertino-afrl]

Neat, I'll try to get on this soon(tm).

[johnathan-convertino-afrl]

Ok, so I've fixed the issue on my end. Though it looks like python 3.9 and up is broken due to a numpy version conflict. Nothing to do with this commit so I'm leaving it broken.

Radiant SDC test passes and fixed.

[olofk]

Alright. Picked and pushed! Thank you for your contributions.