feat: add duplicate connection context menu action

Closes #136

src/i18n/locales/en.ts

@@ -411,6 +411,7 @@ export default {
     confirmDeleteTitle: "Delete Connection",
     confirmDeleteMessage: 'Are you sure you want to delete "{name}"? This cannot be undone.',
     editConnection: "Edit Connection",
+    duplicateConnection: "Duplicate Connection",
     newQuery: "New Query",
     viewData: "View Data",
     editStructure: "Edit Structure",

src/i18n/locales/zh-CN.ts

@@ -403,6 +403,7 @@ export default {
     confirmDeleteTitle: "删除连接",
     confirmDeleteMessage: "确定要删除「{name}」吗？此操作不可撤销。",
     editConnection: "编辑连接",
+    duplicateConnection: "复制连接",
     newQuery: "新建查询",
     viewData: "查看数据",
     editStructure: "编辑表结构",