Add webp support to Image Library in CI4

@nicojmb,

Actually, I just checked.  PHP does have a webp function ( https://www.php.net/manual/en/function.imagewebp.php ).  Depending on the version of PHP that you have it may already be available to you.  No need to integrate it.

Hi, i'm refer to add in Image Manipulation Class, to use with "crop", "fit", etc functions.