VK_IMAGE_USAGE_STORAGE_BIT is always enabled for vkImage, this
increases memory bandwidth in some platforms.
This CL changes the behavior to enable VK_IMAGE_USAGE_STORAGE_BIT
when necessary.

Bug: angleproject:3904
Test: angle_end2end_tests
Test: angle_deqp_gles2_tests
Change-Id: I8ffd37efa8d99d04328fa6232de0755be3273d9e
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1857799
Commit-Queue: Sunny Sun <sunny.sun@arm.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>