Vulkan/D3D12: Make resource transitions explicit, remove the Vulkan auto-transition pass

[xen2]

PR Details

Stacked on #3337.
Counter-proposal to #3329: instead of adding automatic barrier tracking to D3D12, resource transitions are now explicit at the renderer level on all backends.
This removes stopgap and temporary code from old implementation and align all platforms as intended.

Changes

• Compute dispatches (ComputeEffectShader) transition their bound textures explicitly, based on effect reflection.
• Vulkan Clear now leaves targets in their write layout, matching D3D12.
• Read-only depth is driven by the bound view's DepthStencilReadOnly flag, with an explicit transition where ForwardRenderer binds it, instead of layouts baked into the pipeline.
• The Vulkan per-draw auto-transition pass (TransitionBoundResources) is deleted, along with the unused D3D12 ResourceTracking scaffolding.
• With pipelines no longer forcing render pass restarts, the render pass instance stays open across pipeline switches.

Related Issue

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My change requires a change to the documentation.
• I have added tests to cover my changes.
• All new and existing tests passed.
• I have built and run the editor to try this change out.