Update webgpu/types to 0.1.50

[Kangz]

This makes toneMapping optional which required updating a few tests to
use the nullish coalescing operator when accessing it.

New vertex formats are added that require updating capability_info.ts
(and tests for unorm8x4-bgra is added at the same time).

Finally dictionary types for copies are renamed throughout the CTS even
if deprecated aliases are available.

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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.)
• Test have be tested with compatibility mode validation enabled and behave as expected. (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]

cast shouldn't be needed anymore I think

Suggested change

	case 'unorm8x4-bgra' as GPUVertexFormat: {
	case 'unorm8x4-bgra': {