Vulkan: support format aliasing in texture images glBindImageTexture specifies the format which should be used to interpret the texture data and this format is independent from the texture's own internal format. This change allows the VkImage's format to be mutable to handle glBindImageTexture calls with different formats. Bug: angleproject:3885 Test: dEQP-GLES31.functional.image_load_store.*.format_reinterpret.* Change-Id: Ia1ad762b4ccae0f510c8b4918781234fcf51c5f1 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2222610 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Tim Van Patten <timvp@google.com>