Updating cadence ops with new name space, rebasing 6 optimized ops (#6407)

* Main backup (#12)

* Add nnlib as submodule

* Adding nnlib submodule

* Integrated nnlib API unde backends/cadence/hifi

* Fix review comments on PR#3

* Add nnlib as submodule

* Adding nnlib submodule

* Integrated nnlib API unde backends/cadence/hifi

* Fix review comments on PR#3

* Incorporated feedback from Meta team.

* lint errors fixed

* Adding Sub operator optimized version

* Add optimization for add, mul operators

* Adding Div operator

* Modified div mod to cover truncate and floor modes

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Co-authored-by: cad-audio <86048415+cad-audio@users.noreply.github.com>
Co-authored-by: cad-audio <cad_audio_tflm@cadence.com>

* Adding sigmoid optimizations

* Adding tanh optimizations

* Fixing review comments in 5483

* Adding cflags to prevent compilation halts

* Adding cflags to prevent compilation halts

* Changing name space of optimized ops; Remove unused ops from file

* fixed lint issues.

* Namespace updates for cadence ops, adding 6 optimized ops

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Co-authored-by: cad-audio <86048415+cad-audio@users.noreply.github.com>
Co-authored-by: cad-audio <cad_audio_tflm@cadence.com>