feat: Code importer

[Ast3risk-ops]

Describe the feature

Add the ability to import code from a remote file (whole file, specific lines, starting/ending at [word], etc)

i.e.

```ts{2} line-numbers url=<link-to-raw-file>
```

or as a component:

:codeimporter{url=<url> title=title (other parameters from the codeblock)}

or something similar to pymdownx.snippets.

Additional information

• Would you be willing to help implement this feature?