...and recommended pulse width configuration for A4988

The timing value should be properly set for ALL boards. The compiler will check and set maximum step rate calculations based on those values.

- Stepper bugs fixed
- Support MIXING_EXTRUDER with Linear Advance
- Miscellaneous cleanup

- Respect axis max acceleration limits instead of forcing a fixed acceleration value.
- The `junction_unit_vec` ensures proper handling of entry and exit speeds even when the axes involved have different limits.

Part of #10688

Co-Authored-By: ejtagle <ejtagle@hotmail.com>

- Add an option to retry G29, optionally executing a G-code procedure after each failed probe.

This is an initial cut for feedback, updated for 2.0.x.

Chamber temperature is currently reported along with hot end and bed
temperatures to serial. The format is just like that used for hot end
and bed temperatures, but using 'C' prefix. As there is no heater,
target is always 0. Is this appropriate, is there a better way to report
chamber temperatures?

Chamber temperatures are not reported on the LCD in any way.

When auto chamber fan is enabled, it currently just uses the same
temperature threshold as the other auto controlled fans.

As the chamber temperature is not connected to any heater, it doesn't
undergo mintemp/maxtemp monitoring. This would need to change in the
future if chamber heating became a feature.

Some users may prefer to hide the position updates on the `LIGHTWEIGHT_UI` altogether. This leads to an even less cluttered display (it also saves on SPI traffic and one byte of RAM).

Followup to #9832

Fix #9208

- This status screen uses the ST7920 character generator to greatly
  reduce SPI traffic and MCU load when updating the status screen.

- Has been tested with the RepRapDiscount Full Graphics Smart Controller
  but should work with any LCD that uses an ST7920 or fully compatible
  controller.

Counterpart to #9632

Updating I2C position encoders to enable babystepping and Babystep XY when using the ecm microstep correction method. Also changed default method to ECM microstep.

* Add option to use Neopixel as case light

* Apply CASE_LIGHT_USE_NEOPIXEL to example configs