[DirectX] Implement Shader Flag Analysis for `AdvancedTextureOps`

[bharadwajy]

Set function-level flag if

• one of DXIL::OpCode::TextureLoad, DXIL::OpCode::SampleLevel, DXIL::OpCode::SampleCmpLevelZero, DXIL::OpCode::SampleGrad, DXIL::OpCode::SampleCmp, DXIL::OpCode::Sample, DXIL::OpCode::SampleBias, DXIL::OpCode::SampleCmp, DXIL::OpCode::SampleCmpBias:Grad is used and has no constant operand OR
• one of DXIL::OpCode::SampleCmpLevel, DXIL::OpCode::TextureGatherRaw is used.

NOTE: there's concern that this list may not be complete (eg writeable MSAA textures may not be covered here) so someone picking up this issue will need to do some research here.

AC:

Add tests to verify correctness of analysis.