Add ability to configure cache directory for image conversions in @sveltejs/enhanced-img

Describe the problem

Using the @sveltejs/img:enhanced package generates a large number of cacheable converted image variants in various sizes/formats. This process also takes a long time to run the more images are processed and the more variants that are requested.

The vite-imagetools plugin supports caching these artifacts, which @sveltejs/img:enhanced also supports as of v0.2

It does not seem to be possible to use the configuration options that are built into the vite-imagetools plugin to specify where these cached build artifacts should be saved though when using @sveltejs/img:enhanced.

Describe the proposed solution

I would like to be able to configure the upstream vite-imagetools cache options for use in @sveltejs/enhanced:img.

The upstream PR is here and the documented configuration object for cache options is here.

Perhaps having a config passthrough in the vite.config.js file could be an acceptable solution?

import { enhancedImages } from '@sveltejs/enhanced-img';
export default defineConfig({
  ...
  plugins: [
    enhancedImages({
      cache: {
        dir: './node_modules/.cache/imagetools'
      }
    })
    ...
  ]
});

Alternatives considered

I have setup a cache using the default location that vite-imagetools uses but I would like to manually specify the cache location and bring it outside of the node_modules folder.

Importance

nice to have

Additional Information

No response

Start by reading the @sveltejs/enhanced-img package entry points and its integration with vite-imagetools, then compare the upstream cache options linked in the issue. Use the vite.config.js example as the intended interface; done means callers can provide cache settings such as dir and those settings control where converted image artifacts are stored.