Expand/Collapse code block (parity with web)

[emorrp1]

Your use case

What would you like to do?

Have code blocks rendered collapsed by default, expandable on tap.

Why would you like to do it?

To avoid having to use an external pastebin provider, parity with web (Implemented in #5559).

How would you like to achieve it?

Have you considered any alternatives?

No response

Additional context

No response

Are you willing to provide a PR?

No

[mnaturel]

I guess we should also look how it behaves now in iOS if we decide to implement this on Android so that every clients is aligned.