Issue #4270: Recursive option for files through API

What does this MR do?

• Adds recursive param to tree API request. With this param we can get all repository paths in a single request.
• Related old github pull request

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Requested in #4270 (closed)

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• CHANGELOG entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the style guides
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Requested in #4270 (closed)