add test script

plugin/dapp/x2Ethereum/cmd/build/testcase.sh

+#!/usr/bin/env bash
+source "./allRelayerTest.sh"
+
+function x2Ethereum() {
+    if [ "${2}" == "init" ]; then
+        return
+    elif [ "${2}" == "config" ]; then
+        return
+    elif [ "${2}" == "test" ]; then
+        echo "========================== x2Ethereum test =========================="
+        set +e
+        set -x
+        MainTest 1
+    fi
+}