Implement QMI8658 gyro/accelerometer support

[DvdGiessen]

This implements basic support for the QMI8658 IMU, which is for example used on a number of off-the-shelf Waveshare RP2040 boards (I'm using this one, see my branch with the board config here).

This is a very basic implementation, making use of the MIT-licensed code from Waveshare to implement communications with the IMU. It uses the GP2040 I2C abstraction, and I've added a simple configuration for it that for now only allows enabling/disabling it.

Sharing it here as a draft PR; in case I don't find the time to finish polishing this up with extra settings, calibration, etc it might hopefully still be useful to others. :)

[mikepparks]

Glad to see someone taking advantage of the new Aux structures. Given that we're in the middle of rolling a release, this will likely need to move off to the next version to give us time to get hardware to check it out.

• Good catch on the Relative sensor change. I added Relative fairly late in the dev work and didn't update those.
• I would suggest fixing the indentation issue you have for optional QMI8658Options qmi8658Options = 28; in config.proto to match the others.
• It's preferred that we avoid the old naming for I2C terms, preferring "target" or "device".
• Debug output functions such as printf should either be removed or excluded via a conditional define for their usage, as they can potentially impact performance.

[DvdGiessen]

Thanks for the feedback!

• I would suggest fixing the indentation issue you have for optional QMI8658Options qmi8658Options = 28; in config.proto to match the others.

Fixed! I didn't notice my editor used .editorconfig to switch to tabs here; already had to fight it a bit for example due to the trim trailing whitespace option resulting in a lot of unrelated whitespace changes I had to exclude from my commits. :) Might make for another small but useful PR similar to #436.

• It's preferred that we avoid the old naming for I2C terms, preferring "target" or "device".
• Debug output functions such as printf should either be removed or excluded via a conditional define for their usage, as they can potentially impact performance.

I copied the QMI8658 library directly from Waveshare, so I didn't look into cleaning these up yet. I've addressed these two points for now; there's more things in these files that could be cleaned up but at least for now it is somewhat functional.