add copy button to code blocks

[yeus]

Is your feature request related to a problem? Please describe. I would like to have an optional copy button for code blocks.

Describe the solution you'd like When a code block e.g. like this:

appears, there should be a copy button next to the code block

Describe alternatives you've considered I tried showCopy, but it only works for the entire document.

Additional context

it works in github :). see:

print("you can copy this!!")