Separate `Module` in `ModuleValidation` and `ModuleExecution`

[plafer]

Module should be split into 2 different traits:

• ModuleValidation which contains all *_validate() methods
• ModuleExecution which contains all *_execute() methods

Modifications to Router:

• Router::get_route_validation() -> Option<&dyn ModuleValidation>
  • previously Router::get_route()
• Router::get_route_execution() -> Option<&dyn ModuleExecution>
  • previously Router::get_route_mut
• Router::has_route() split in has_route_validation() and has_route_execution()
  • we should provide default implementations for these too based on get_route_*()