webnn: Support quantize and dequantize in tflite converter
Implement WebNN quantize operation with TFLite QUANTIZE builtin
operator, only scalar zero point and scale can be supported at
current stage.
The dequantize operation is implemented with TFLite DEQUANTIZE
builtin operator, and emulate the unsupported case with the expression
output = (input - zeroPoint) * scale.
Bug: 40206287
Change-Id: Ifea831b0fdb95dd33147310175c8c089ee0a341a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5967060
Reviewed-by: Reilly Grant reillyg@chromium.org
Reviewed-by: ningxin hu ningxin.hu@intel.com
Commit-Queue: Junwei Fu junwei.fu@intel.com
Cr-Commit-Position: refs/heads/main@{#1376810}