[modules][messages] mission: LLA waypoints in 1e7deg instead of float

A 32bit float has 23bits for the mantissa, which is a bit more than 7 digits.
Since you already use 3 digits to represent the part to the left of the decimal point, that leaves about 4 digits for the rest..
So in the worst case of 180deg you have a resolution of only ~3m!

With 1e7deg 32bit int you get ~1cm resolution.

Rotorcraft part: Also removed the removed the altitude conversion from geoid alt to ellipsoid alt,
requiring the alt in the message to already have ellipsoid alt.
No idea why it assumed geoid alt in message in the first place... we have ellipsoid alt for other messages as well...

addresses first part of #984