Document NaN support in interfaces and NaN usage in CLI

[Ryanf55]

Purpose

Document what is currently supported by ROS when using NaN/infinity values for floating points in messaging.

Why

sensor_msgs/msg/BatteryState tells users to use NaN, but there's not info in the docs on working with NaN's. This documents what currently exists. I plan to improve support for NaN's across the ROS ecosystem because they are heavily used in the aerial messages of REP-147 and in MAVLink.

Ticket

Closes #4135