[SPIR-V] Static class member initializer not implemented

Description
Static class member initializer not implemented for SPIR-V.

Steps to Reproduce
dxc -T ps_6_0 -E main -O0 -spirv

class S {
    float4 b;
};

class T {
    static S N;
};

S T::N = {1., 2., 3., 4.};

float4 main(float4 input: A) : SV_Target {
    return 1.0;
}

https://godbolt.org/z/soMxxsjYj

Actual Behavior

<source>:11:10: error: initializer for type 'S' unimplemented
S T::N = {1., 2., 3., 4.};

Succeeds with DXIL backend.

Environment

• DXC version: 8e9cefa1d5074142a05641f694e58b68812b35a0
• Host Operating System: Linux

Start by running the reported dxc command with the HLSL reproducer and compare its SPIR-V failure with the successful DXIL backend result. Trace the SPIR-V handling of the static class member initializer for S T::N; done means the reproducer compiles successfully to SPIR-V with the initialized values preserved.