[Feature Request]: Python RunInference transform should be Schema-Aware

### What would you like to happen?

Currently, Python RunInference transform takes [parameterized input/output types](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/ml/inference/base.py#L59) that may or may not be Schema-Aware. This makes it harder to use this transform for cases where we need a Schema-Aware/portable type (for example, Multi-language, SQL). For such cases, the transform may or may not be usable depending on the ModelHandler used. I think we need to update this transform so that users can directly operate on Schema-Aware input/output PCollections.

### Issue Priority

Priority: 2

### Issue Component

Component: run-inference