Export TFJS/CoreML with fused NMS

[leeclemnet]

What does this PR do?

Bakes in NMS to TFJS and CoreML exports to simplify client-side logic

• inferencejs client was already using TF NMS, this just brings it inside the model artifact
• roboflow-swift should use native coreml NMS for best performance

Thresholds for both are configurable at runtime.

Type of Change

• Breaking change (fix or feature that would cause existing functionality to not work as expected).
  • This is technically a breaking change but tfjs and coreml exports are not yet usable on platform.

Testing

• I have tested this change locally
• I have added/updated tests for this change

Test details:

https://github.com/roboflow/roboflow-train/pull/762

local tfjs inference with nms baked in

https://github.com/roboflow/inferencejs/pull/51

local coreml inference with nms baked in

roboflow/roboflow-swift#27

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code where necessary, particularly in hard-to-understand areas
• My changes generate no new warnings or errors
• I have updated the documentation accordingly (if applicable)

Additional Context