Star imports from mlserver.codecs not working

[jklaise]

For example:

from mlserver.codecs import *

Throws an error:

Traceback (most recent call last):
  File "/home/janis/.conda/envs/py310/lib/python3.10/site-packages/IPython/core/interactiveshell.py", line 3460, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-2-b8cc62508f29>", line 1, in <module>
    from mlserver.codecs import *
AttributeError: module 'mlserver.codecs' has no attribute 'StringRequestCodec'

This is likely because __all__ is out-of-date with the actual imports. I haven't tested other sub-packages, but it might be worth looking at these.

P.S. I'm not a big fan of __all__ and star imports in particular, the main issue is that the existence of __all__ gives rise to two public APIs which may diverge (as it has in this case).