Allow for more refined (non-syntax) highlighting in code

[Filip-FK-Kwiatkowski]

v-mark is an excellent tool for highlighting key points in text, but doesn't seem to work with code blocks. While line highlighting is very appealing and extremely useful, it has some obvious limitations - it always highlights the entire line, but sometimes we wish to draw attention to a particular portion of that line.

Ideally, I would love it if code blocks could support some form of integration with v-mark, for example to dynamically encircle a given section (span, if you will) of code. Maybe it could be specified somewhere next to the Shiki's parameters.

I have considered a workaround of trying to find a component like arrow but in form of a circle. Didn't find it. Worst case scenario I could use an arrow, but it's just not the same. Plus it would potentially have to be updated every time the code snippet changes (that's the case for both supplied <arrow> and the hypothetical <circle>).