Add tests for multi-draw-indirect

[kainino0x]

Spec issue: https://github.com/gpuweb/gpuweb/issues/1354

We can initially develop these tests against the feature name "chromium-experimental-multi-draw-indirect" (available in Chrome Canary behind chrome://flag#enable-unsafe-webgpu) and then graduate them to "multi-draw-indirect" eventually once the spec moves forward.

[kainino0x]

Dawn currently has some tests here; we would want to make sure CTS covers at least those cases, as well as more exhaustive tests of various scenarios.

• https://source.chromium.org/chromium/chromium/src/+/main:third_party/dawn/src/dawn/tests/end2end/MultiDrawIndirectTests.cpp
• https://source.chromium.org/chromium/chromium/src/+/main:third_party/dawn/src/dawn/tests/unittests/validation/MultiDrawIndirectValidationTests.cpp

[beaufortfrancois]

@kainino0x I've started working on validation tests at https://github.com/gpuweb/cts/pull/3962. Let me know if I'm heading in the right direction.

[beaufortfrancois]

@kainino0x I've started working on validation tests at #3962. Let me know if I'm heading in the right direction.

Gentle ping