Patch upstream omegaconf issue #830

[rsokl]

Closes #170

For users using omegaconf 2.1.1 or earlier, we provide a patch of an upstream bug.

Before:

# bug from omegaconf
>>> A = make_config(x=1)
>>> B = make_config(x=[1, 2], bases=(A,))
>>> instantiate(B)
{'x': 1}

After:

# hydra-zen 0.4.0 circumvents bug
>>> A = make_config(x=1)
>>> B = make_config(x=[1, 2], bases=(A,))
>>> instantiate(B)
{'x': [1, 2]}

We achieve this by detecting the particular conditions for which this bug occurs:

• The user is not using a newer version of omegaconf, where this bug is fixed
• and.. the config sets a mutable default value via default-value factory
• and.. the config inherits from one or more parent dataclasses
• and.. the parent also provides a field of the same name
• and.. the parent's field is not a default-value factory

and only under these circumstances will we automatically transform

make_config(x=[1, 2], bases=(A,))

to

make_config(x=builds(list, [1, 2]), bases=(A,))

which ensures that the resulting config will instantiate as-expected.

We provide this automatic support for all use-cases of make_config and builds. We cannot provide this automatic support for hydrated_dataclass, however we do still detect the conditions and raise a HydraZenValidationError in such circumstances.