[ENHANCEMENT] Improve namespace packaging

[ewianda]

Is your feature request related to a problem? Please describe.
The bazel python ruleset relies on the standards for laying out name space packages. The existing setup doesn't follow that as such it is not possible to have both the core and the eval packages in the same bazel managed code based
Describe the solution you'd like
Ensure that top level packages have no __init__.py files or include the __path__ = __import__('pkgutil').extend_path(__path__, __name__) in the init.py files

Additional context
Similar issue was reported previously
Arize-ai/openinference#398