Tests for staging buffer layout not matching source layout in `Queue.writeTexture`

[andyleiserson]

#7893 suggests that our test coverage here may not be good enough.

[ErichDonGubler]

Andy in our team meeting: One interesting question to resolve here is that we expected ASan to catch something like this. However, Firefox ASan runs did not catch this. Why was that?

[andyleiserson]

Linked PR adds a test. The test fails if run under asan in the wgpu tree without the fix for #7893, indicating that not finding this before was due to missing coverage as opposed to a problem with the asan setup.