Specify range constraint in parameter descriptor when bounds<> validator is present

[bjsowa]

The ParameterDescriptor message contains fields for specifying the range for float and int parameters:

https://github.com/ros2/rcl_interfaces/blob/43ffb7b6df6a98a1a35d0932d148ad12de549594/rcl_interfaces/msg/ParameterDescriptor.msg#L27-L36

This is used, for example, in rqt_reconfigure to display sliders for choosing the parameter value.

I would love it if these fields were actually used in this library,. Seems like they can be easily populated from the values passed to the bounds<> validator.