Add diagnostics support back to noetic branch

[clalancette]

In PR #39, we are rewriting the phidgets_drivers to use libphidget22 (and get us access to phidgets on VINT hubs). To keep the size of that PR down, and to keep the code consistent, we removed diagnostics from the one node that already had it (the IMU node).

This is an issue to track adding diagnostics back to the entire library so all of the nodes have it.