List acceptence for scale parameter

Hi!

I modified the coreml framework, which results with scale parameter in convert operation to accept a list, rather than a single float.

Here are my changes:

I can generalize this to different shapes just like bias parameter. Should I create a PR for this? Would be this helpful? Is there a specific reason why team has not implemented this functionality?

Start at the Core ML convert operation and compare its scale parameter handling with the existing bias parameter handling. Determine the supported list shapes and whether scale should accept them, then verify that conversion succeeds for the intended shapes; the issue names no files or tests.

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