[Feature Request] [SPIR-V] Support float16 texture types

[godlikepanos]

Hi. Is there a chance we could get float16 texture support?

When compiling this:

Texture2D<float16_t4> tex;

float4 imageMain(float4 svPosition : SV_Position) : SV_Target0
{
    return tex[svPosition.xy];
}

with -enable-16bit-types DXC returns the following error: error: 16-bit texture types not yet supported with -spirv