Add API validation tests on the extension subgroup-size-control

[Jiawei-Shao]

This patch adds the API validation tests on the extension subgroup-size-control:

• Enabling subgroup-size-control on the creation of device should also enable subgroups.

Issue: #4640

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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 c045004):

+webgpu:api,validation,capability_checks,features,subgroup_size_control:enables_subgroups:* - 1 cases, 1 subcases (~1/case)
-TOTAL: 281256 cases, 2322907 subcases
+TOTAL: 281257 cases, 2322908 subcases

[Jiawei-Shao]

@kainino0x @jrprice PTAL, thanks!