Feature Request - Downscale image & Save as Webp

### Ability to Downscale Image to Specific Resolution

Currently, the Diffusion Bee image generator has the ability to upscale images to a specific resolution, but it does not have the ability to downscale images to a specific resolution. It would be beneficial to have this feature as it would allow users to generate images at the exact resolution needed for their blog posts, without having to manually resize the image afterwards.

### Ability to Save Image as WebP

In addition to the ability to downscale images to a specific resolution, it would also be useful to have the option to save the generated image as a WebP file. WebP is a modern image format that provides superior compression compared to other formats like JPEG and PNG, which means that images saved as WebP will take up less space on the user's website and will load faster for their visitors.

Both of these features would improve the functionality of the Diffusion Bee image generator for blog post images, and make it an even more valuable tool for content creators.