* Optimize target_extruder, ignore T with mixing
* Give G-code Tn parity with tool_change

See if this has any deleterious effect on motion planning by slicers that inser their own jerk and acceleration controls. The problem I see is that these settings can take effect on blocks already in the planner, and the only way around this would be to shadow these settings in planner blocks and use the shadowed settings in the planner.

* Add parser.seen for multiple parameters
* Fix M666, use !seen for report
* Synchronize on M204, M205

* Clean up Temperature PID
* Improve EEPROM read/write/validate
* Group `SINGLENOZZLE` saved settings
* Group planner saved settings
* Group filament change saved settings
* Group skew saved settings
* Group `FWRETRACT` saved settings

- Move FWRETRACT to the planner
- Combine leveling, skew, etc. in a single modifier method
- Have kinematic and non-kinematic moves call one planner method

- Drop `max_jerk` with `JUNCTION_DEVIATION`
- Add `max_e_jerk_factor` for use by `LIN_ADVANCE`
- Recalculate `max_e_jerk_factor` when `junction_deviation_mm` changes
- Fix LCD editing of `junction_deviation_mm`

`M204` is often used by slicers to set acceleration depending on perimeter, infill, etc., so Marlin's answers are flooding the serial windows. Silence `M204` according to the philosophy that setter commands should only send a reply if no parameter is given.

Addressing #7707