Ability to trim pitch angle for level flight

[DzikuVx]

Closes #6561

The fw_level_pitch_trim can be used to trim pitch angle and is separated from the board orintation option.
To make it more user friendly, positive values means that nose should be raised UP for level flight.

The next step would be to add it to the Adjustments section and remove ROLL and PITCH board adjustments from Configurator GUI and Adjustments

[avsaase]

This is much more intuitive. However I think the existing board alignments should stay in the configurator in case people want to mount their flight controller in other orientations than flat with the arrow pointing forward. But perhaps in the configurator it can be simplified similar to the magnetometer alignment, with the fine adjustments left to the CLI.

[DzikuVx]

@avsaase board ROLL and PITCH board adjustments were used only for trimming. I do not know of any practical usage of those besides trimming. YAW stays as it's required for the correct board orientation (forward arrow).

For the super rare cases when user mounted the board on the strange angle and not flat, CLI adjustments stay

[wx4cb]

@avsaase board ROLL and PITCH board adjustments were used only for trimming. I do not know of any practical usage of those besides trimming. YAW stays as it's required for the correct board orientation (forward arrow).

For the super rare cases when user mounted the board on the strange angle and not flat, CLI adjustments stay

so instead of just changing the roll alignment in the configurator for a board that is mounted upside down ( I have one here in my glider where the only way is upside down in the belly hatch), i would have to do it in the cli?

[DzikuVx]

@wx4cb Yes. On the other hand we might leave it as it is but with a red note not to use it to trim the airplane