Add MAX17048 lipo fuel gauge

[dhskinner]

This PR adds MAX17048 lipo fuel gauge as a new power sensor for the telemetry & power module

Its linked to https://github.com/meshtastic/protobufs/pull/540 that added the necessary enums to telemetry.proto

This follows pretty much same pattern as other Telemetry sensors, as well as adding requisite code to integrate this sensor into the device power functionality in similar fashion to the axp192 power management IC

This one is a do-over because I screwed up the original PR with an issue raising the PR from another organisation account.

Appreciate your review and any comments

[fifieldt]

Welcome back :)

[dhskinner]

Welcome back :)

Thanks :)