feat: add ad_save_images_dir

[bluelovers]

#688

[Bing-su]

First of all, could you please include an explanation for why this is needed? I can't agree with the need for this option.

[bluelovers]

the current ad image is saved as the same as the image directory
this means we can't easily split and browser images with ad images and images generated

also, some other extensions like controlnet are save detect_map in other directories too

we should not put all these files into one folder because it will be very hard to find them

split it into different folders is better

[Bing-su]

Isn't that a subjective opinion?
I like this structure with the final and intermediate images together.

[bluelovers]

Isn't that a subjective opinion? I like this structure with the final and intermediate images together.

ok, now it only enables when not empty

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud