- Add `axis_t`, `extruder_t`, `heater_t`, and `fan_t` to eliminate ambiguity, improve type safety.
- Regularized getter/setter argument order and naming.
- `setAxisPosition` no longer stacks moves in the buffer, allowing it to be called repeatedly on each touch ui tap.
- Implement better manual moves for `EXTENSIBLE_UI` (#12205)
- Calling `setAxisPosition_mm` no longer buffers the entire move to the new position, but instead causes small moves towards it to be made during the idle loop. This allows the user to adjust the destination even after the move has started and makes the UI feel much more responsive.
- As suggested by @ejtagle, the new code keeps the planner buffer full to ensure smooth motion without stops and starts.
- Change `En`, `Hn` and `FANn` to zero-based indices.
- Labels consistent with the rest of Marlin code.

...and replace with delays for all HAL_STM32 boards.

In reference to #12175

For some features it can be useful to write custom text in a menu item. This commit provides helpers to make this easier.