Qualcomm AI Engine Direct - Adding QNN backend support for atan2 core ATen ops

[qti-horodnic]

Summary

Adding support for the atan2 ATen op by a decomposition pass using the identity:

        atan2(y, x) =
            atan(y/x)        if x > 0
            atan(y/x) + π    if x < 0, y >= 0
            atan(y/x) - π    if x < 0, y < 0
            +π/2             if x = 0, y > 0
            -π/2             if x = 0, y < 0

Note that the op atan2.out is also added as a target, even though that op is converted to atan2.default by torch.export. The decomposition would still work in case the conversion was missed somehow.

Test plan

python backends/qualcomm/tests/test_qnn_delegate.py -k TestQNNQuantizedOperator.test_qnn_backend_atan2 --model SM8750 --host aisw-vm19-labsd --device 8afa1dd9 --build_folder build-android
python backends/qualcomm/tests/test_qnn_delegate.py -k TestQNNFloatingPointOperator.test_qnn_backend_atan2 --model SM8750 --host aisw-vm19-labsd --device 8afa1dd9 --build_folder build-android

[pytorch-bot]

🔗 Helpful Links

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[qti-horodnic]

@pytorchbot label "release notes: qualcomm"

[qti-horodnic]

@abhinaykukkadapu Hi, is there anything you wanted me to modify with this PR?

[abhinaykukkadapu]

@abhinaykukkadapu Hi, is there anything you wanted me to modify with this PR?

Ohhh i forgot to merge this, as i was waiting for CI results at that time, will merge now