push bluetooth-le behind feature flag

[PeterGrace]

The introduction of btleplug module includes the requirement of libdbus-1-dev which is not available for all cross-compilation platforms.

This PR ensures that the BLE code is behind a feature flag so that people who want said functionality, can use it.

This PR also updates the protobufs to the latest version in the repository. I can rebase without this, if necessary.

(cc @lukipuki )

[CLAassistant]

All committers have signed the CLA.