feat(vcs): clone from the repositories of your GitHub account (#1125)

The Clone Repository dialog lists GitHub next to Repository URL: the repositories of the account gh is signed in to, searchable; picking one fills URL and directory, double-click or Enter clones. Clone URL follows gh's git_protocol. Clone sources are a workbench contribution (registerCloneSource); gh_account_repos needs no project.

Closes #750

src/platform/locales/text/zh.json

@@ -5804,5 +5804,13 @@
   "Pin": "固定",
   "Unpin": "取消固定",
   "Project default": "项目默认",
-  "The node executable this script runs on; empty uses Settings › Languages & Frameworks › Node.js.": "运行此脚本的 node 可执行文件；留空则使用“设置 › 语言和框架 › Node.js”中的解释器。"
+  "The node executable this script runs on; empty uses Settings › Languages & Frameworks › Node.js.": "运行此脚本的 node 可执行文件；留空则使用“设置 › 语言和框架 › Node.js”中的解释器。",
+  "Loading repositories…": "正在加载仓库…",
+  "GitHub repositories are listed with the": "GitHub 仓库列表需要",
+  "Search repositories": "搜索仓库",
+  "Repositories": "仓库",
+  "No matching repositories": "没有匹配的仓库",
+  "No repositories": "没有仓库",
+  "fork": "复刻",
+  "archived": "已归档"
 }