Collapse/expand option for code blocks

[Ben-ADFA]

Ref. 3584

Issue Checklist

• I confirm that this feature request has not been previously suggested.
• I agree to follow the project's code of conduct.
• I have checked and verified that I am using the latest version of Code on the Go from GitHub or App Dev for All.

Additional terms

• I understand that feature requests are subject to evaluation and may not be implemented immediately.
• I agree to provide additional details if needed for a clearer understanding of the requested feature.

Feature description

From Vkrm (@sirvkrm) on Telegram:
"Hello, i have a feature suggestion for code editor, like add a code block closer same as Vscode/CodeOSS like if a function code block is about 100 lines then show only first line which can be opened by clicking on a arrow ⬆️⬇️ same like Vscode/CodeOSS, as maybe it'll not gonna be hard as our Code editor already have code blocks function to map down lines for code blocks which now just needs a collapse and expand system so users can work on big code files.

Check the picture for more info, as my English isn't good enough to explain it perfectly."

Use Case

When working with large blocks of code

Benefits

Viewing ease