19897: Return ENOTSUP when the user tries to make a file in a project

19897: Return ENOTSUP when the user tries to make a file in a project

Before this commit, the NotImplementedError is propagating up to
catch_exceptions, which turns it into EIO. "I/O error" sounds like a
problem with the underlying systems and stresses out users. "Operation
not supported" should better communicate to the user that they're doing
something unexpected and should double-check their work.

Arvados-DCO-1.1-Signed-off-by: Brett Smith <brett.smith@curii.com>