Dont present CAN items if CAN is not present in hwdef

This causes a build error

Replicate:
1. Any board without CAN
2. Click on Rangefinders twice to remove all of them

this will fail since the first click enables all rangefinders, including DroneCAN, which ticks the DroneCAN box, next click removes all Rangefinders but does not uncheck the DroneCAN causes a build failure(which is generally desired behavior since we cant know if a box with driving dependencies is or is not desired)

solutions:
Best: don't present any CAN related options anywhere if the hwdef for the board does not have a "CAN1" define
Easiest: clicking a partially filled section, first REMOVES all the selections, next click Adds all, instead of the other way around...

btw, I have not found another feature that depends on onboard hardware(there may be and I don't recognize it)....I thought ENET might, but currently we have no build option that depends on having that on board...and including sensor drivers for missing onboard sensors might waste space but does not cause a build error

Reproduce this on a board whose hwdef lacks CAN1 by opening Rangefinders, clicking twice, and observing the build failure. Trace the Rangefinders and DroneCAN option handling and the CAN1 hwdef check; done means CAN-related options are not presented without CAN1, or the documented toggle behavior prevents the invalid selection and the build succeeds.

Written by the indexing model from the issue text.