fix(接口测试): 修复引用的case可以修改关联文件的缺陷

--bug=1019480 --user=王孝刚
【接口测试】github#19536，接口自动化模块，引用的接口case也可以修改请求体的关联文件，但修改后不会生效。应该禁止修改
https://www.tapd.cn/55049933/s/1291458

api-test/frontend/src/business/definition/components/ApiVariable.vue

@@ -57,7 +57,7 @@
 
 
         <el-col v-if="isActive && item.type === 'file'" class="item">
-          <ms-api-body-file-upload :parameter="item" :id="id"/>
+          <ms-api-body-file-upload :parameter="item" :id="id" :is-read-only="isReadOnly"/>
         </el-col>
 
         <el-col v-if="type === 'body'" class="item kv-select">

api-test/frontend/src/business/definition/components/body/ApiBodyFileUpload.vue

@@ -17,11 +17,12 @@
             :http-request="upload"
             :beforeUpload="uploadValidate"
             ref="uploadLocal">
-            <el-button type="text"> {{ $t('permission.project_file.local_upload') }}</el-button>
+            <el-button type="text" :disabled="isReadOnly"> {{ $t('permission.project_file.local_upload') }}</el-button>
             <span slot="file"/>
           </el-upload>
         </div>
-        <el-button type="text" @click="associationFile">{{ $t('permission.project_file.associated_files') }}</el-button>
+        <el-button type="text" @click="associationFile"
+                   :disabled="isReadOnly">{{ $t('permission.project_file.associated_files') }}</el-button>
         <i class="el-icon-plus" slot="reference"/>
       </el-popover>
     </div>
@@ -77,7 +78,11 @@ export default {
     id: String,
     default() {
       return {}
-    }
+    },
+    isReadOnly: {
+      type: Boolean,
+      default: false
+    },
   },
   methods: {
     exist() {