[circle-mlir/tools-test] Enable tests for AddOp in import/export

This will enable value tests for AddOp in import/export tests.

ONE-DCO-1.0-Signed-off-by: SaeHie Park <saehie.park@gmail.com>

Author: seanshpark

circle-mlir/circle-mlir/tools-test/circle-impexp-test/test.lst

@@ -3,3 +3,6 @@
 # AddModel(test_model)
 # ImportModel(test_model)
 #
+
+AddModel(Add_F32_R4)
+AddModel(Add_F32_R4_C1)