Add collapsable/expandable code blocks

[izmalk]

Problem to Solve

Sometimes we have bigger code fragments to illustrate in docs (like a full IAM schema of 350+ lines).

Current Workaround

Code-block that takes a long time to scroll through.
Or a link to download a file without a preview.

Proposed Solution

We should have the ability to add a code block that will show 5-10-20 lines of code by default and then have a dimming effect (or something to show that this is not) and a link/button to expand it to the full version. Also, the button to copy code block contents should work in both collapsed and expanded states.

Ideally, we need a way to collapse the block back after you expanded it and witnessed its great scale.

Additional Information

[alexjpwalker]

Are we sure this is a good idea- that is, the best UX we can deliver as a fix to the issue of having very long code snippets that take a long time to scroll through?

From what I can tell, CockroachDB doesn't do this at all in their docs (https://www.cockroachlabs.com/docs/stable/query-spatial-data.html, https://www.cockroachlabs.com/docs/stable/bulk-update-data.html). Granted, these code snippets are 50 lines long, rather than 350.

My gut instinct says that 350-line code snippets should be provided as file downloads - or perhaps displayed on a dedicated page that has no content other than the code snippet. Can you show screenshots of a doc page you want to add that uses this feature?