layers: Add error codes for parameter_validation

layers: Add error codes for parameter_validation

Add error codes to the parameter_validation layer:
- Add parameter_validation::ErrorCode enum defining common parameter
  validation errors to parameter_validation_utils.h
- Replace the '1' in parameter_validation log_msg calls with the
  appropriate error code
- Add parameter_validation error code documentation to
  vk_validation_layer_details.md
- Remove 'typedef enum' declaration requirement for error code
  enumerations from vk_layer_documentation_generate.py; It will
  now recognize error code enmerations declared wihtout the typedef

Change-Id: Icf18b9124000159f7436f66e48a95d0c58047a07