Add uint8 quantization example for NEON

Add uint8 quantization example for NEON

This example performs a simple matrix multiply operation.
It includes both full precision and low precision GEMMs.
Uses square matrices with known values by default (for easy vaidation).
Uses random values when user specifies matrix sizes.

Signed-off-by: Diana Bite <diana.bite@arm.com>
Change-Id: I269d1e20dbd231c48667751e71758b2e90ec72a2
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/c/VisualCompute/ComputeLibrary/+/223887
Tested-by: bsgcomp <bsgcomp@arm.com>
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/2924
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Manuel Bottini <manuel.bottini@arm.com>