Depth stencil layout may change while we build the render pass,
depending on the read/write access been made. Right now we are always
inserting a layout change barrier at the start of render pass.  Later on
when the read/write property changes, we insert another layout change
barrier. Similarly, we maintain the attachmentOps and
RenderPassDesc::mPackedColorAttachmentRangeAndDSAccess as we changes
read/write access. This makes code quite commplicated. This CL moves
mReadOnlyDepthStencilMode from FramebufferVK to CommandBufferHelper
object and we only maintain that boolean while we updating the
read/write access. Then at the end of render pass or when depthStencil
image is deleted, we update attachmentOps and mRenderPassDesc and layout
transition all at once and only done once. This simplifies the read only
depth stencil mode implementation a lot.

Bug: b/168953278
Change-Id: Ie263b4526c82a9858e5d1f141ea58f499187a3ca
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2432075
Commit-Queue: Charlie Lao <cclao@google.com>
Reviewed-by: Tim Van Patten <timvp@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>