[DirectX] DXIL container shader flags are incorrect when using native low precision

[bogner]

If we build any shader with clang-dxc -enable-16bit-types, we fail the validator.

Given x.hlsl:

RWBuffer<half> Out : register(u0);
[numthreads(1,1,1)] void main() {
  Out[0] = 0;
}

We see:

$ clang-dxc -enable-16bit-types -T cs_6_4 -Fo x.o x.hlsl
error: Container part 'Feature Info' does not match expected for module.
Validation failed.

clang-dxc: error: dxv command failed with exit code 1 (use -v to see invocation)

This looks like a problem with NativeLowPrecision vs UseNativeLowPrecision in DXContainerConstants.def

[farzonl]

Before this change (e66b731) I was seeing error: Container part 'Feature Info' does not match expected for module. 2499 times. After this change I now only see 221 cases.