Execution Tests for Long Vectors

[pow2clk]

Execution tests for HLSL long vectors are needed to verify that vectors over size 4 are supported on all platforms.

Is your feature request related to a problem? Please describe.

See #7066 for compiler implementation. Vectors have long been limited to four elements and many existing code paths have that expectation ingrained. Whether these vectors are represented as native vectors or scalarized, testing could reveal important flaws. Scalarized vectors might be revectorized in backends and expected to be no more than 4 elements in some contexts.

Describe the solution you'd like

Existing tests for DXIL intrinsics should be leveraged to test for long vectors. This should involve a few different sizes and will probably best be done by modifying the tests to be more length robust.