✨ Markdown: Backlink Support

### Is your feature request related to a problem? Please describe.

_No response_

### Describe the solution you'd like

It would be nice if CodeEdit support backlinks in markdown: when type `[[`, a small window hover and show all your markdown file's filename, you can select one of them to create backlink, after `[[SOME_MD_FILENAME]]` finished, the file `SOME_MD_FILENAME.md` would also create a backlink that mention the file that linked to it, which might be a snippet of markdown text:
```markdown
## Backlinks
* [[Something that links here]]
* The block of text in the referencing note which contains the link to [[Sample note]].
* Another block in that same note which links to [[Sample note]].
* [[A different note that links here]]
* This is a paragraph from another note which links to [[Sample note]].
```
This might be a little dirty to add to a code editor, as this feature is usually supported by Note APPs like [Roam Research](https://roamresearch.com), [Obsidian](www.obsidian.md), [Logseq](https://github.com/logseq/logseq), and [Notion](www.notion.so), etc. But it would be really cool for a native APP to support this as all these APPs are not macOS native (most of them based on Electron).

### Describe alternatives you've considered

Using Note APPs that support backlink feature, like [Roam Research](https://roamresearch.com), [Obsidian](www.obsidian.md), [Logseq](https://github.com/logseq/logseq), and [Notion](www.notion.so).

### Additional context

Examples for backlinks:
- Notion

- Logseq

此 issue 未指定原始檔案、測試或進入點。先定位 Swift 編輯器的 Markdown 處理邏輯，並了解檔案如何被發現與轉譯；以 [[...]] 選取、已儲存的連結，以及與範例相符的產生反向連結內容來定義完成標準。

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