feat: add progress token support and extend Request interface (#352)

- Add PaginatedRequest and ReadResourceRequest to Request sealed interface
- Add default meta() and progressToken() methods to Request interface
- Add _meta parameter support to request classes:
  - ReadResourceRequest, GetPromptRequest, CallToolRequest
  - CreateMessageRequest, ElicitRequest, CompleteRequest, PaginatedRequest
- Add builder methods for progress token configuration
- Add message field to ProgressNotification
- Maintain backward compatibility with existing constructors
- Add _meta field to the InitialRequest record

Signed-off-by: Christian Tzolov <[email protected]>

Author: tzolov