Include wiki diffs in `hasCode`

[fregante]

Example:

https://github.com/pixiebrix/pixiebrix-extension/wiki/Web-Extensions-behaviors/_compare/664a8f7^...664a8f7

There might be more URLs.

[cheap-glitch]

Source files diffs should probably be included too, e.g.:

https://togithub.com/fregante/github-url-detection/edit/main/index.ts

The thing is, there's not really any "code elements" on the page until you make an edit and click on the "Preview" tab.

[fregante]

Nah that's a bit much. To target previews we have to add specific listeners and I don't really want to add selection-observer there too 😬

[cheap-glitch]

Nah that's a bit much. To target previews we have to add specific listeners and I don't really want to add selection-observer there too 😬

It could still be useful to include those URLs for some CSS-only features, e.g. hide-diff-signs. But I guess this should be done in the feature-specific code then.