FullyConnected layer integration changes

[vnileshdaiict]

Following changes have been made :

1. Integration of float32, 4-bit & 16-bit fully_connected kernels.
2. Integration of matmul kernels for float32, 4, 8, 16-bit batched fully_connected cases.
3. Data-type based registration for fully_connected operator.
4. Addition of compile flag to include / exclude HiFi floating point optimized fully_connected kernel.

BUG=none

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[rascani]

@vp-cad - The formatting errors can be fixed with:

tensorflow/lite/micro/tools/ci_build/test_code_style.sh --fix_formatting

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