Add option to render "Search result excerpt" as field

Thanks for suggesting this feature!
However, it does seem like a very niche functionality. I think I’ll have to wait whether more people show interest in this before proceeding with this ticket. In any case, the description of the feature would have to be significantly improved (I had to look at the code, and not just quickly, to understand what this feature does), and this would also need tests. But I’d suggest first waiting whether there is actual interest before working on that, to avoid wasted effort.