QC8 NHWC Convolution operator

- xnn_create_convolution2d_nhwc_qc8 and xnn_setup_convolution2d_nhwc_qc8 APIs
- Unit tests

PiperOrigin-RevId: 380283916
diff --git a/src/xnnpack/operator.h b/src/xnnpack/operator.h
index 11c77e5..4adf549 100644
--- a/src/xnnpack/operator.h
+++ b/src/xnnpack/operator.h
@@ -49,6 +49,7 @@
   xnn_operator_type_convolution_nchw_f32,
   xnn_operator_type_convolution_nhwc_f16,
   xnn_operator_type_convolution_nhwc_f32,
+  xnn_operator_type_convolution_nhwc_qc8,
   xnn_operator_type_convolution_nhwc_qs8,
   xnn_operator_type_convolution_nhwc_qu8,
   xnn_operator_type_copy_nc_x32,