xyz_grid: add raw_mode

[wkpark]

Description

• This is another attempt to input raw text lines
• for some inputs with "\n" included, (x.strip().find("\n") != -1 case)
• it does not affect any functionality, except one accidentally inputs \n chars in the X/Y/Z values

Screenshots/videos:

Checklist:

• I have read contributing wiki page
• I have performed a self-review of my own code
• My code follows the style guidelines
• My code passes tests

[AUTOMATIC1111]

XYZ UI is already very complex and I'd rather not add more to it, especially considering this change will not play nice with restoring UI from infotext.

[wkpark]

(rebased and conflict resolved.)