Clean up deprecated .sampleType/.copySrc from kTextureFormatInfo

[kainino0x]

Verified:

• webgpu:api,operation,command_buffer,copyTextureToTexture:* passing
• webgpu:shader,execution,expression,call,builtin,textureDimensions:* passing (fully, after rebase over [shader/execution] Fixes for textureDimensions() #3413)

All the other changes should be trivial enough that there isn't danger of breaking anything. Hopefully.

Part 5 of Issue: #2495

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Requirements for PR author:

• All missing test coverage is tracked with "TODO" or .unimplemented().
• New helpers are /** documented */ and new helper files are found in helper_index.txt.
• Test behaves as expected in a WebGPU implementation. (If not passing, explain above.)

Requirements for reviewer sign-off:

• Tests are properly located in the test tree.
• Test descriptions allow a reader to "read only the test plans and evaluate coverage completeness", and accurately reflect the test code.
• Tests provide complete coverage (including validation control cases). Missing coverage MUST be covered by TODOs.
• Helpers and types promote readability and maintainability.

When landing this PR, be sure to make any necessary issue status updates.

[kainino0x]

@lokokung PTAL (not sure if you get notified when I just request a review)

[kainino0x]

Fixed merge conflict in latest commit.