texture2d - getVulkanImage and support for Texture2DUsage::Attachment (#3632)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Adrian Cojocaru <adrian.cojocaru92@yahoo.com>
Co-authored-by: Bart Louwers <bart@emeel.net>

include/mbgl/vulkan/texture2d.hpp

@@ -80,6 +80,7 @@ public:
 
     const vk::ImageLayout& getVulkanImageLayout() const { return imageLayout; }
     const vk::UniqueImageView& getVulkanImageView() const { return imageAllocation->imageView; }
+    const vk::Image& getVulkanImage() const { return imageAllocation->image; }
     const vk::Sampler& getVulkanSampler();
 
     void copyImage(vk::Image image);