consult-mark, consult-line, consult-outline should highlight matches in preview

[minad]

While the current line is highlighted, the matched strings are not. The current completion style or the selectrum highlight filter should be used to obtain the highlights.

[minad]

@oantolin Since you wrote the orderless package (which I am also using btw), I wonder if you know a generic way of obtain the matches of the current completion, in order to show them in the buffer for preview, additionally to being shown already in the minibuffer. I haven't found something obvious quickly but I didn't dig very deep.

[minad]

I think this can be implemented as follows:

1. Obtain the completion candidate stringvia all-completions, orderless will highlight the matches via face properties
2. Extract face properties and create overlays which can then be presented in the buffer for preview

But for now I have no intention to implement this. But if someone is interested, PRs are welcome.