[BUG] outdir_samples and outdir_grids are ignored (and a few other problems)

[system1system2]

1. At the moment, this extension only looks into the following default folders (as defined in WebUI config.json):

• outdir_txt2img_samples
• outdir_img2img_samples
• outdir_extras_samples
• outdir_txt2img_grids
• outdir_img2img_grids

completely ignoring custom folders defined in:

• outdir_samples
• outdir_grids

2. at least on macOS, even if you manually force a custom-defined folder in outdir_txt2img_samples, the Image Browser never updates its txt2img tab. If you force a custom-defined folder in outdir_img2img_samples and outdir_extras_samples, instead, it works as intended.

3. at least on macOS, the tab Favorites harvests images from every subfoder in /stable-diffusion-webui/ folder, displaying images found in /stable-diffusion-webui/repositories/ and /stable-diffusion-webui/extensions/ and many other places.

4. at least on macOS, the tab Others doesn't allow to specify any custom folder, returning the error You have not permission to visit /Custom/Folder. If you want visit all directories, add command line argument option '--administrator', More detail here even if that folder has the same permission as the default folders.