Make Transform executor compatible with TFT versions 0.13 and 0.14
Make Transform executor compatible with TFT versions 0.13 and 0.14

Since there were breaking changes (introduced by CL/254803791), we need to special code here to handle both versions.  A new function is introduced to fetch the Schema proto associated with a DatasetMetadata.

PiperOrigin-RevId: 255020381

tensorflow/tfx,tensorflow/tfx