Allow sidebar extensions to open links in new sidebar tabs

Fairly self-explanatory, I have an extension I'm building with a customisable set of links, and I'd like those links to be able to be opened in a copilot browser tab, like github.com links can, rather than an external browser, like all other links currently do.

首先跟踪侧边栏扩展目前如何处理链接，并将其行为与在 Copilot 浏览器标签页中打开的 github.com 链接进行比较。当侧边栏扩展中的可自定义链接改为在 Copilot 浏览器标签页中打开，而不是在外部浏览器中打开时，即表示完成。

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