[php-src] Issue #11353: Add support to reprocess gain maps

Issue: https://github.com/php/php-src/issues/11353 Author: gregbenz ### Description A new "**gain map**" standard is designed to allow sharing a single image file which is optimized for both proper HDR (high dynamic range) display where supported and optimized SDR (standard dynamic range) display where either HDR is not supported or the browser does not understand gain maps. A JPG gain map built with a base SDR image and gain map for HDR therefore offers a great way to bridge the transition to the future where HDR is widely supported. It also offers improved tone mapping on displays with modest HDR capability (ie <1000 nits peak brightness). JPG gain maps are already supported under Chrome Canary v116 desktop as well as Android (and looks amazing on an Apple laptop or Pixel 7 Pro). PHP (and or the Wordpress media library) does not understand the gain map standard and as a result destroys it when derivative media (such as thumbnails) are created. Expected result: the HDR and color profile metadata should be retained, and the auxiliary image should be scaled/cropped in a consistent manner if the primary image is altered. ====== Gain map samples and specification: https://helpx.adobe.com/camera-raw/using/gain-map.html These images will render best with Chrome Canary on an M1 or M2 MacBook Pro (or any monitor with 600+ nits, make sure HDR support is toggled on if using Windows). More info on HDR: https://gregbenzphotography.com/hdr/