Additional validation of buffer-texture copies

[andyleiserson]

Adds some more buffer-texture copy validation. I am declaring that this fixes #7936, although there are still problems with buffer-texture copies, see #7946 and #7947.

This PR enforces:

• Offset for copies to/from compressed formats must be aligned to the block size
• Offset for copies to/from depth stencil formats must be 4B aligned.
• Temporarily enforces that all buffer-texture copies be 4B aligned, pending a fix for wgpu imposes a 4B alignment for buffer initializations but fails to respect it #7947.
• Disallows multisampled textures for both T2B and B2T (previously only one checked for multisampled textures)

Testing
Enables a sampling of relevant CTS tests, but some of the tests still have a mix of passing and failing variants and I didn't try to exhaustively list every passing case in test.lst.

Squash or Rebase? Squash

Checklist

• Run cargo fmt.
• Run taplo format.
• Run cargo clippy --tests. If applicable, add:
  • --target wasm32-unknown-unknown
• Run cargo xtask test to run tests.
• If this contains user-facing changes, add a CHANGELOG.md entry.

[andyleiserson]

This comment previously noted which commits belonged to this PR vs. #7935, but that no longer applies since the other PR has been merged and this one rebased.