move clip skip sdxl option to sdxl section

[dhwz]

Description

• just moves the clip skip sdxl setting to the sdxl config subsection

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

[w-e-w]

while I think it makes sense I also like some opinion from other people

reason to merge

• SDXL setting should be put in SDXL section

reason to not merge

• CLIP settngs should be put together in one place
• • as currently it's grouped with CLIP_stop_at_last_layers