Add basic Operator interface

- C facing interfaces
- Activation layer descriptor

Partially Resolves: COMPMID-4512

Signed-off-by: Georgios Pinitas <georgios.pinitas@arm.com>
Change-Id: I8530748fff178ca46d61bf2e40d3e543e93f340b
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/5908
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Michele Di Giorgio <michele.digiorgio@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
diff --git a/filelist.json b/filelist.json
index 9562cc7..061c3e8 100644
--- a/filelist.json
+++ b/filelist.json
@@ -11,6 +11,7 @@
   "c_api": {
     "cpu": [
       "src/c/AclContext.cpp",
+      "src/c/AclOperator.cpp",
       "src/c/AclQueue.cpp",
       "src/c/AclTensor.cpp",
       "src/c/AclTensorPack.cpp",