Transmit broadcasting interval for neighbors

[ajmcquilkin]

What does this PR do?

Currently devices and clients are unable to know the duration at which other nodes broadcasting neighbor information packets. This PR adds in a field to allow devices to know exactly how often it should expect to hear from each neighbor.

Checklist before merging

• [x] All top level messages commented
• [x] All enum members have unique descriptions

[thebentern]

@ajmcquilkin let's retarget this at 2.2-proposed-changes branch

[thebentern]

@ajmcquilkin I made the change the 2.2 branch. I'll regen the protos in the corresponding firmware branch PR