add sc7u22 imu support.

[Ncerzzk]

Hi, we are producing a micro elrs receiver with pwm output and imu support.
some short introduction may be seen in: https://humpbacklab.com/en/lightfin-nano.html

we are very interested in this project, and hope the code could be merge in.
Samples are available and we will send them soon to contributors of this project.

the first pr is about the imu sc7u22 driver.

Thank you, feel free to comment.

[frankiearzu]

Will move your changes to the new branch "gyro-4.1-merge" that is up to date with the master branch.
I would recomend increase the refresh rate from 250hz to something greater than 800hz. (From comments on the Madgwick/Mahoney implementation for drones).

Also since it ignores accelerometer readings outside 0.9g to 1.1g, I will change the Accelerometer range to be 4G instead of 16g. makes it less jumpy.

Can you do the changes for the Acce range, and refresh/ODR rate please. Also if you are still in development, if you can connect the Interupt line to the processor, that avoid an extra read to the I2C data-ready status.

[Ncerzzk]

Thank you. I will do these changes recently.
the IRQ line may connect to ESP32 c3 in VDD_SPI（18, could be configured as gpio) in next hardware version.