COMPMID-2549: Add GLES Runtime Context interfaces.

* Creates interfaces and concrete classes
* Ports GCActivationalLayer
* Adapts test framework and relevant tests

Change-Id: Ide36cd65ebf185958db3c4a5bebd630fcb2f39b3
Signed-off-by: Georgios Pinitas <georgios.pinitas@arm.com>
Reviewed-on: https://review.mlplatform.org/c/2199
Reviewed-by: Pablo Marquez <pablo.tello@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
diff --git a/arm_compute/runtime/CL/CLHelpers.h b/arm_compute/runtime/CL/CLHelpers.h
index 84f155a..6d00026 100644
--- a/arm_compute/runtime/CL/CLHelpers.h
+++ b/arm_compute/runtime/CL/CLHelpers.h
@@ -29,8 +29,10 @@
 
 namespace arm_compute
 {
+// Forward declarations
 class CLRuntimeContext;
 class ICLKernel;
+
 /** This function creates an OpenCL context and a device.
  *
  * @note In debug builds, the function will automatically enable cl_arm_printf if the driver/device supports it.