Operation tests for setImmediates

[shaoboyan091]

Implement operation tests for setImmediates in ComputePassEncoder, RenderPassEncoder, and RenderBundleEncoder.

• Add basic execution tests for scalar, vector, and struct types.
• Add tests for partial updates and multiple updates (using range verification).
• Add tests for pipeline switching (compatible and incompatible).
• Add tests for large data (maxImmediateSize) with range verification.
• Add tests for TypedArray arguments with offsets.
• Add tests for mixing render pass and bundle execution.

Issue: #

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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.
• Test descriptions are accurate and complete.
• Tests provide complete coverage (including validation control cases). Missing coverage MUST be covered by TODOs.
• Tests avoid over-parameterization (see case count report).

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

[github-actions]

Results for build job (at 509b754):

+webgpu:api,operation,command_buffer,programmable,immediate:basic_execution:* - 39 cases, 39 subcases (~1/case)
+webgpu:api,operation,command_buffer,programmable,immediate:update_data:* - 3 cases, 3 subcases (~1/case)
+webgpu:api,operation,command_buffer,programmable,immediate:pipeline_switch:* - 2 cases, 2 subcases (~1/case)
+webgpu:api,operation,command_buffer,programmable,immediate:use_max_immediate_size:* - 3 cases, 3 subcases (~1/case)
+webgpu:api,operation,command_buffer,programmable,immediate:typed_array_arguments:* - 33 cases, 33 subcases (~1/case)
+webgpu:api,operation,command_buffer,programmable,immediate:multiple_updates_before_draw_or_dispatch:* - 3 cases, 3 subcases (~1/case)
+webgpu:api,operation,command_buffer,programmable,immediate:render_pass_and_bundle_mix:* - 1 cases, 1 subcases (~1/case)
+webgpu:api,operation,command_buffer,programmable,immediate:render_bundle_isolation:* - 1 cases, 1 subcases (~1/case)
-TOTAL: 285993 cases, 2344970 subcases
+TOTAL: 286078 cases, 2345055 subcases

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