Call to undefined function file_create_url() in CssOptimizer

I have applied above patch.
In Drupal, there is no direct method generateString() provided by the FileUrlGeneratorInterface. The correct method name to generate a file URL as a string representation would depend on the specific use case and context.

This error related to drupal 10 compatibility.
I am working on it.

Please review patch.

I've rerolled the patch because of several issues. Based on #2 and #6, here's a new patch with solves the following:

• #6 threw this error Error: Object of class Drupal\Core\Url could not be converted to string in Drupal\flysystem\Asset\CssOptimizer->rewriteFileURI() (line 43 of /var/www/html/web/modules/contrib/flysystem/src/Asset/CssOptimizer.php because $this->fileUrlGenerator->generate($path) returned a Core/Url object so I added the function to get the URI.
• Fixed phpcs warnings/errors.
• Fixed phpstan warning errors including parent constructor.

#6 patch was wrong for 2.1.x branch due to I've already applied the previous patch. Attached rerolled patch with #7 fixes for 2.1.x-dev branch

The last patch caused an issue for me where base: prefixes were added to asset URLs, causing assets to not load. Calling getUri on the Url object is not enough because you can end up with internal URI's, you have to call toString in order to generate a publicly accessible URL.

Rerolled patch to apply to 2.1.x-dev branch after merging in other MRs, merge and marked as fixed. Thank you all!