Add a flag to NOT fetch parts from web-of-registries as needed during validation

[cjmyers]

The default should be fetch parts from web-of-registries during validation, but it should be possible to turn this off, if desired.

[3ach]

Is this supported in libSBOLj?

[cjmyers]

Not currently through the command-line, but it would not be hard to add. We would just need a switch that says add all registries as possible sources of parts. The issue here is worded a bit strange, since I would assume the flag would enable/disable WoR support.