cunumeric: cunumeric does not issue unimplemented warnings for functions in submodules

OK now we are getting somewhere.

@manopapad I think coverage just does not work with np.random in general. I’m not sure if it never worked, or if it was recently broken somewhere. This will require some investigation. The coverage codepaths are already fairly convoluted and unpleasantly special-cased.

For modules where we have partial coverage, I like the current behavior of warning for each missing function separately, but only the first time it’s called.

If we’re talking about a whole module missing, then it would be nice to warn once, on the first use of any function in that module. But if that’s too hard, then warning on the first use of each function from the module would still be OK IMHO.

Noting the possibility of API coverage reporting could be an option in all scenarios I assume.