Clarify behavior when both body and url parameters are provided

[ahanel13]

There is ambiguity in how the extension should handle scenarios where both body and url parameters are provided.

Task:

• Add right-click behavior on a request:
  • If URL (GET) parameters exist, show a dropdown option for URL
  • If body parameters exist, show a dropdown option for BODY
• Optionally include a top-level Add to all button (note the likelihood of testing both at once is low)

Acceptance Criteria:

• Right-click menu displays the correct dropdown(s) depending on request contents
• Selecting URL or BODY applies the parameter to the appropriate area
• If “Add to all” is implemented, it applies to both places reliably and is covered by tests
• Documentation updated with screenshots and example