Differentiate between model output and postprocessing output

[wyli]

The metadata states what the network produces as its output but if the postprocessing transform sequence does a lot to change the shape and format of this output there will be a disconnect between what is expected and the actual results. One example is a bundle which produces a certain number of channels that don't directly relate to classes which is then transformed into an output with a different number of layers representing one-hot encoded multiclass labels

• update spec
• update existing bundles output spec (model zoo)
• downstream app. (monai label) reading output spec for bundle validation

[ericspod]

We have updated the schema to support this, there are a few bundles which should be changed to reflect this difference, but also MONAILabel and other tools require some changes to correctly pick up which result they expect.