Fix Snapmaker Luban support

[Golumpa]

In the latest version of Luban, the formatting has changed slightly. (I am not sure when it was changed, I only just started using Luban)

Was
;thumbnail: data:image/png;base64,

Now
;Thumbnail:data:image/png;base64,

This adds Luban support back. This will only work with newly sliced gcodes.

Had to rename to txt due to github restrictions but here is a newly sliced benchy.
3DBenchy_1706529863352.gcode.txt

[jneilliii]

Could you do me a favor and validate the change I just committed to your PR, which should allow for both use cases?

;[Tt]humbnail: ?data:image/png;base64,(.*)[\r\n]

[Golumpa]

Yeah I'm not good with regex but this would be a much preferable way of doing it.

[Golumpa]

Now that I have finished my 20 hour print, I can confirm it is working as intended.

I downloaded the GCode from the original implementation #91 and both the new and old GCode displays an image now

[jneilliii]

Thanks for confirming.