Add namedtuple for BME680 Sensor

The following discussion from !147 (merged) should be addressed:

• @rahix started a discussion: (+2 comments)

  I think it would be nice if this is a namedtuple. I haven't used those from the C side so far but I'd guess lib/micropython/micropython/py/objnamedtuple.h contains the necessary functions. Might make sense to push this into a followup-MR though if it's too complicated ...