create testcase for src at rpm at

suite2cases/function_test/pkg_test/at/at.json

@@ -0,0 +1,10 @@
+{
+    "path": "$OET_PATH/testcases/function_test/pkg_test/at/at",
+    "machine num": 1,
+    "cases": [
+        {
+            "name": "test_at_function_basic",
+            "desc": "Test basic functionality of at package"
+        }
+    ]
+}