Co-Authored-By: MarcelMo <marcelmo@users.noreply.github.com>

Fixes #14476

- Use the return value from probe_pt during `G34`
  Eliminate the assumption that probe_pt leaves current_position set to values relative to the probed points. This is not always true, depending on the raise_after argument.
- Add '`E`' argument to `G34` command allowing stowing between each probe.

- Avoid white flash on TFT (re)init. Unlike Graphical LCD, the TFT init color may be full white if the backlight is on during init.

- Add a conditional for delayed backlight init which can be applied to any backlit display.