DX12: Align copies b/w textures and buffers when D3D12_FEATURE_DATA_D3D12_OPTIONS13.UnrestrictedBufferTextureCopyPitchSupported is false

[ErichDonGubler]

Connections

• Likely resolves [d3d12] Panic in end_encoding  #5285.
• A case we need to handle for [d3d12] Support padded rows_per_image for 3D texture writes #4150.

Testing

• @teoxoy and I proved on some custom DLLs copied from an old Windows machine that this works, both on older WARP adapters and when forcefully done in updated DX12 runtimes. So, we're definitely not breaking anything! It's hard to set up an environment to specifically test this, though.

Squash or Rebase?

rebase plz

Checklist

• If this contains user-facing changes, add a CHANGELOG.md entry.

[ErichDonGubler]

Got the CI issue resolved! I was definitely doing something wrong. 👉🏻👈🏻 From community chat:

@ErichDonGubler:

I just paired with Teo, and we actually FIGGERED IT OUT!

@teoxoy and I sideloaded a bunch of DLLs from an ancient Windows 10 computer I had, which happened to have a WARP adapter that did not support low-alignment buffer-to-texture copies.

...turns out I accidentally swapped the alignment requirement branches. 😅

We had to work around:

• Not having the right DLLs (because new versions have lower alignment needs) and stealing them from an old machine I happened to have around.
• Crashing when trying to compile indirect buffer validation shaders (because old versions?)
• Feature unification working against us when trying to use WGPU_VALIDATION_INDIRECT_CALL=0
• Erich being dumb and necessitating debugging in the first place

It was an hours-long adventure, lemmetellyawhat.

@teoxoy:

It was fun :)

@cwfitzgerald:

oh boy!

that sounds like an adventure indeed

[teoxoy]

Looks good overall but we should also enable some CTS tests like the one in #5285.

[teoxoy]

These seem swapped.

[teoxoy]

I think we can unwrap here, since it would simplify the code and 0 sized copies shouldn't appear at the hal level.