[HLSL][SPIR-V] Add `StorageBufferArrayNonUniformIndexing` extension for `RWStructuredBuffer` with non-uniform index

[luciechoi]

Per SPIR-V Specification, StorageBufferArrayNonUniformIndexing extension needs to be added when accessing RWStructuredBuffer with a non-uniform index.

RWStructuredBuffer<uint4> ReadWriteStructuredBuf[64];

[numthreads(64,1,1)]
void main(uint3 GTID: SV_GroupThreadID) {
    ReadWriteStructuredBuf[NonUniformResourceIndex(GTID.x + 1)][98][0] = 99;
}

Support for non-uniform index is added in #162540 but the extension is missing for RWStructuredBuffer.

Child of #161852

[luciechoi]

@s-perron