Drop basicsr dependency

[akx]

Description

Post #14425, we only used basicsr for img2tensor and tensor2img; this PR vendors the relevant bits (RGB tensors/images only, RGB<->BGR conversion always) into a couple of functions to get rid of basicsr as a direct dependency altogether.

I also noticed I'd screwed up with the typing for restore_face, so that gets fixed too.

Screenshots/videos:

None. I did double-check the test-outputs for face restoration, and they look like they did before. I also checked that the RGB/BGR conversion is necessary; they were very screwy otherwise. 😁

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]

it seems basicsr is used by realesrgan so it's going to be installed anyway

realesrgan==0.3.0
├── basicsr [required: >=1.4.2, installed: 1.4.2]

[akx]

@w-e-w we don't depend on realesrgan since #14425 either :)

https://github.com/AUTOMATIC1111/stable-diffusion-webui/pull/14425/files#diff-2284b86f286dc7e0ea4bd09a0ec20c78fbb17d6724d7f0053e78428d0715bbb1

[w-e-w]

@w-e-w we don't depend on realesrgan since #14425 either :)

ohhh that's new

[AUTOMATIC1111]

There is possibility for some extension to break if it uses the library assuming webui requires it.