[d3d9] Handle sampling from DS_READONLY properly

[K0bin]

Fixes #3593

Instead of an enum or read/write flags like we discussed, I took a step back and thought about what CommonTexture::m_hazardous was actually used for. It's used to track whether the image has been transition to the hazard layout (GENERAL or FEEDBACK_LOOP). That's it. The actual hazard tracking happens in the device.

So the image layout strategy for DS is now as follows:

• If there's a hazard with depth write enabled, we transition to LAYOUT_FEEDBACK_LOOP and keep using that, just like we do for color RTs.
• If there's a hazard with depth write disabled (so technically not a hazard), we use LAYOUT_DEPTH_READ_ONLY for the render pass and transition back to the regular layout afterwards.

Before we would transition between LAYOUT_FEEDBACK_LOOP and LAYOUT_DEPTH_READ_ONLY per render pass.