Move registration of --no-pantsrc to global_options.py to resurrect it

It's a bit of a special case since it is used before the options are parsed. I left that part as is.

Testing Done:
Manual

Reviewed at https://rbcommons.com/s/twitter/r/1170/
Sync of https://github.com/pantsbuild/pants/commit/7bd913cce56797d87d2909bbb912d6abd11b7d21