Support TensorFlow Saved Model's with legacy_init_op and main_op

[JakeRadMSFT]

System information

• OS version/distro: All
• .NET Version (eg., dotnet --info): ML.net 0.11

Issue

• What did you do?
  Tried to load SavedModel.
• What happened?
  Received a table not initialized error.
• What did you expect?
  Table initialization is specified in legacy_init_op. I expected the operation(s) in legacy_init_op to be executed after loading the model.

See https://www.tensorflow.org/api_docs/python/tf/saved_model/Builder#add_meta_graph for more information on legacy_init_op and main_op.

[JakeRadMSFT]

@zeahmed adding a bug to track the issue. Can you add any relevant logs or exception details?

[rosebyte]

Closing as the requested information wasn't provided.