This commit adds an 'IgnoreObjectConversionErrors' option to the
validation testing framework in 'k8s.io/apimachinery' and exposes it
via 'pkg/api/testing'.
This is useful for fuzzing tests where we might want to skip object
versions that cannot be converted from the internal version (e.g. due to
missing fields or incompatible types in older versions) but still want
to test validation for the versions that *can* be converted.
The 'autoscaling' group versions are added to 'TestVersionedValidationByFuzzing'
with this option enabled.
This makes a bold assumption: that the errors (count and basic content)
will be the same across versions. If this turns out to be untrue, this
may need to get more sophisticated. It should fail obviously when we
hit that edge.
