Add optional namespace to Settings Sync API URL

MR: Add optional path parameter to Settings Sync en... (!171165 - merged)

Description

We will pass the extensions marketplace context as a route parameter to the Settings Sync API to prevent modifying the VSCode fork. To ensure backwards compatibility, we will make this an optional parameter.

Acceptance Criteria

• Making a request to the Settings Sync API endpoints with the new parameter should return a successful response.
• Does not break existing functionality: a request to the endpoints without the optional parameter (current behavior) should return a successful response.

Technical Requirements

• Update this line to add the optional namespace → resource '/settings_sync(/:settings_context_id)' do