Add sensor health checks

[kylc]

On startup sensors should be polled to ensure they are functioning correctly. For example, a simple check of a WHO_AM_I would ensure that communication is working.

If an error is detected then an error should be sent and the vehicle should not arm.

[kylc]

Basic health check code is implemented. Need to implement the specific checks for each driver.

[yoos]

Sensors have failed to initialize in cold or damp weather, and health checks would have saved a lot of time in previous launch attempts in Utah and Oregon.