Add Copy to clipboard button to code snippets in everywhere possible

[gimantha]

For some code snippet, it would be easy for users to directly copy the code by clicking a button and try out the code. Some code snippets are lengthy and users may have to scroll the pages while copying the code manually. Something like we have in BBE pages

[anupama-pathirage]

This is done except for usecase pages. It is tracked via #6983, hence closing this issue.