Implicit padding testing along the X axis on high priority operators

Add artificial implicit padding testing for the following fixtures:
- Scale
- FullyConnected
- Pooling
- DepthwiseConvolution
- DirectConvolution
- Winograd
- FFT
- GEMM/GEMMLowp

Create utility function that loops through a list of tensor and adds random padding based on the global seed (only for NHWC layer layout).

Remove GEMMLowpAssemblyFixture since it wasn't used
Remove some AssetsLibrary headers since they weren't used

Resolve COMPMID-4161

Change-Id: Ib6f4f7f113ae69b993d7b2a9e04abbf3de8c99fe
Signed-off-by: Giorgio Arena <giorgio.arena@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/5327
Reviewed-by: Michele Di Giorgio <michele.digiorgio@arm.com>
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/tests/validation/Helpers.cpp b/tests/validation/Helpers.cpp
index 7ff2ab6..b53d46f 100644
--- a/tests/validation/Helpers.cpp
+++ b/tests/validation/Helpers.cpp
@@ -325,6 +325,30 @@
     return std::pair<int, int> { min_bound, max_bound };
 }
 
+void add_padding_x(std::initializer_list<ITensor *> tensors, const DataLayout &data_layout)
+{
+    if(data_layout == DataLayout::NHWC)
+    {
+        constexpr unsigned int lower = 1U;
+        constexpr unsigned int upper = 16U;
+
+        std::uniform_int_distribution<unsigned int> distribution(lower, upper);
+        size_t                                      seed_offset = 0;
+
+        for(ITensor *tensor : tensors)
+        {
+            ARM_COMPUTE_ERROR_ON(!tensor->info()->is_resizable());
+
+            std::mt19937 gen(library->seed() + seed_offset++);
+
+            const unsigned int right = distribution(gen);
+            const unsigned int left  = distribution(gen);
+
+            tensor->info()->extend_padding(PaddingSize(0U, right, 0U, left));
+        }
+    }
+}
+
 template void get_tile(const SimpleTensor<float> &in, SimpleTensor<float> &roi, const Coordinates &coord);
 template void get_tile(const SimpleTensor<half> &in, SimpleTensor<half> &roi, const Coordinates &coord);
 template void get_tile(const SimpleTensor<int> &in, SimpleTensor<int> &roi, const Coordinates &coord);