Add support for MPU6886 1kB FIFO buffer to improve IMU sampling precision

[chrisr-sensiml]

Existing library allows for polled sample reads of the MPU6886 IMU sensor. Additions in this pull request add support for the MPU6886 FIFO mode that allow more precise sampling by setting a sample rate for FIFO buffering of sample data with burst reads from the host ESP32 application.

[imliubo]

Hi @chrisr-sensiml , Thanks for the contribution, but it looks like the code style check is not passing.We have a ".clang-format" file in the this repo root path,could you check this style file and commit again?

[imliubo]

Thanks for this improve! Merged!