Update an existing request with complete replacement of editable fields

Updates an existing request by replacing all editable fields with the provided values. This is a full update
operation that replaces the request's content while preserving its identity and system-managed metadata. Only
users with appropriate management permissions can update requests.

Key Features:

• Updates request content including title, description, dates, and priority
• Allows reassigning requests to different users with validation
• Maintains activity tracking and updated timestamps for modified requests
• Validates assignee user IDs to ensure valid assignments
• Returns updated request object with new timestamps and content
• Preserves request identity and system metadata

Authorization Logic:

1. User must have a valid JWT token with program management scopes
2. Token must be valid for this operation
3. User must have permission to update requests in the specified space
4. Assignee user must exist and be valid within the tenant

Usage Example:

Update request details when requirements change, reassign to different team members, or modify deadlines to reflect updated program schedules.