Support syncing assets for other repos

As mentioned in [actions-sync issue 43](https://github.com/actions/actions-sync/issues/43), we need a tool to sync not only actions git repos but also assets (release binaries) from github.com to Github Enterprise Servers. This is especially true for repos like [actions/node-versions](https://github.com/actions/node-versions). Adding the capability for mirroring node-versions and other frequently-referenced assets would be instrumental in reducing traffic to github.com and also avoid rate limits for users of Github Enterprise Server.

首先閱讀 actions-sync issue 43，並檢查此 repository 中現有的 action-repository 和 CodeQL bundle 同步入口。定義應如何發現、傳輸來自 actions/node-versions 等 repository 的 release 二進位檔，以及如何在 GitHub Enterprise Server 上表示這些檔案；該 issue 未指定檔案或測試，因此需要在實作前釐清驗收標準。

由索引模型根據 Issue 內容生成。