Add implementation for inputs and outputs getters to SavedModel

[patlevin]

Motivation

SavedModel currently lacks implementations for the inputs and outputs getters (see Issue #4035).

The model signature already contains all necessary information and invoking getMetaGraphsFromSavedModel() to get the information might result in redundant file I/O and -parsing.

Implementation

This implementation extracts the ModelTensorInfo from the model's signature and removes channel information from the tensor names (e.g. "output:0" is returned as just "output").

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[patlevin]

@googlebot I signed it!

[pyu10055]

Thank you for the contribution, overall looks great, just a minor comment. Also can you added test to these methods?

Reviewable status: 0 of 1 approvals obtained (waiting on @patlevin)

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tfjs-node/src/saved_model.ts, line 213 at r1 (raw file):

    const results = Object.keys(entries).map((key: string) => entries[key]);
    results.forEach((info: ModelTensorInfo) => {
      info.name = info.name.replace(/:\d+$/, '');

the index number should be kept unless it is 0, it represents the which output of the node is designated for the model output.

[patlevin]

@pyu10055 Thanks for the quick feedback! I added tests and changed the name-handling so indices other than zero are kept in the returned input- and output names.

[pyu10055]

Reviewable status: 0 of 1 approvals obtained (waiting on @patlevin)

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tfjs-node/src/saved_model_test.ts, line 523 at r3 (raw file):

        './test_objects/saved_model/model_multi_output', ['serve'],
        'serving_default');
    expect(model.inputs.length).toBe(2)

missing semicolons here and below

[pyu10055]

Reviewed 1 of 2 files at r2, 1 of 1 files at r4.
Reviewable status: complete! 1 of 1 approvals obtained (waiting on @pyu10055)