Ptt/cleanup

[avtoku]

In base rosflight_firmware:
+Moved GNSS data type conversion from mavlink into board
+Removed ublox gnss fix type
+Removed unused variables in rosflight_structs.h associated with unused ublox packets.
+Updated parameters_test.cpp to match param.cpp
+Removed cases in void Mixer::param_change_callback(uint16_t param_id) that don't require action and were causing undesired recursion.

In boards/varmint_h7:
+Created DoubleBuffer interface
+Replaced PacketFifo with DoubleBuffer for sensors since it's more efficient and we only ever used the most recent value read for sensors. Also removed associated, and now unused, #defines in BoardConfig.h's
+Added type conversion for GNSS data to match new rosflight_structs.h
+Removed .clang-format from boards/varmint_h7 (did not run formatter to avoid spurious changes during review)
+Pass header structure into misc_header().
+Added MiscRotatable to misc.h. Used to align sensor with each other and the board axes.
+Removed external SPI in Pixracer Pro version. Replace with 3 GPIO probe outputs and One EXTI input for GPS PPS

Cleanup:
+Replaced build_varmint.sh with unit_test.sh
+Added CMakeFiles to .gitignore
+Added CMakeCache.txt to .gitignore
+Moved read_complete in rosflight_structs.h structures into the header structure as "complete"
+Removed some unused and commented-out code

Todo:

• Run formatter