Add Qidi Plus 4

[liberodark]

The Goal of this PR is to try to upstream change for Qidi Plus 4.
For add Support of this printer.

[Neko-vecter]

The Goal of this PR is to try to upstream change for Qidi Plus 4. For add Support of this printer.

If a PR relate to a specific function of specific printer. That mean the printer require a specific repo to implement. The mainstream only focus the function that every device require. You should using your own repo to make this implement.

For example, every printer will add command SAVE_CONFIG_QD even if the printer is not this one.

-Neko.vecter

[Neko-vecter]

If you want to add this function to Klipper it can be able using the method like Happy-Hare. Add you own file by using ln command.

-Neko.vecter

[Sineos]

1. Please be aware that you need to sign off your PR for the certificate of origin as per point 3 in https://github.com/Klipper3d/klipper/blob/master/docs/CONTRIBUTING.md#what-to-expect-in-a-review, including the rest of the points.
2. As indicated by @Neko-vecter, it is very unlikely that the PR will be accepted in any way:
   • It contains "extras" that are not compatible with the main Klipper philosophy, e.g., gcode_shell_command.py.
   • Only functionality that is beneficial to a larger user and hardware base is accepted, not to a single printer and its specific hardware.
   • Multiple features should always be in separate PRs.