Handle setImmediates command in encoder open-state tests

[shaoboyan091]

The render pass, render bundle, and compute pass command switches listed setImmediates as a parameter but had no matching case. Once an implementation exposes setImmediates, the feature-presence guard no longer skips and the command falls through to unreachable().

Add a setImmediates case to each switch that issues a minimal valid call, keeping the existing feature-presence guards so the cases still skip when the feature is unavailable.

Issue: #4669

---

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 e948437):

 Test case/subcase counts did not change.