COMPMID-3128: Test improvement for GEMMConvolutionLayer on CL and NEON(Function-level)

COMPMID-3128: Test improvement for GEMMConvolutionLayer on CL and NEON(Function-level)

Cleaning up GEMMConvolutionLayer tests by doing the following:

- Remove unnecessary configuration tests
- Remove redundant tests
  > Redundant shapes
  > For large shapes there are already tests for each internal kernel/function
- Test NHWC 1x1 kernel 1x1 stride to stress _skip_im2col
- Stimulate gemm3d to skip col2im
- Test asymmetric padding
- Test batch size equal to one and different than one
- Test fully connected convolution
- Test with a few different padding values
- Test 1D kernel
- Test with FLOOR rounding policy

Change-Id: I88e7009b8e9c991994ed264476c16a79a0de4a68
Signed-off-by: Michele Di Giorgio <michele.digiorgio@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/3150
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Sang-Hoon Park <sang-hoon.park@arm.com>