Add NonSemantic.Shader.DebugInfo.100 options for Nvidia Nsight and/or RenderDoc source debugging

[DannyArends]

What

Adds two compile options that make shaderc emit NonSemantic.Shader.DebugInfo.100, equivalent to glslang's -gV / -gVS:

• shaderc_compile_options_set_generate_nonsemantic_debug_info, equivalent to -gV
• shaderc_compile_options_set_generate_nonsemantic_debug_source, equivalent to -gVS

Additionally, I have wired up matching CompileOptions::SetGenerateNonSemanticDebugInfo() / SetGenerateNonSemanticDebugSource() in the C++ wrapper.

Why

set_generate_debug_info only emits OpLine/OpSource (glslang -g). Tools like NVIDIA Nsight Graphics need NonSemantic.Shader.DebugInfo.100 for function- and call-site-level source correlation (Flame Graph, Top-Down/Bottom-Up Calls). shaderc had no way to request it (see #1391), so callers had to drop to glslang or dxc directly. The pull requests makes these new flag independent from generate_debug_info so plain -g stays available as a fallback for shaders that fail to compile withNonSemantic info enabled.

Usage: a Nsight-ready build

    shaderc_compile_options_t options = shaderc_compile_options_initialize();
    shaderc_compile_options_set_generate_debug_info(options);               // -g:   OpLine/OpSource
    shaderc_compile_options_set_generate_nonsemantic_debug_source(options); // -gVS: NonSemantic + source
    shaderc_compile_options_set_optimization_level(options, shaderc_optimization_level_zero);

-g provides the line table, -gVS provides the call graph; Nsight uses both. Optimization must stay at zero. The size/performance passes can mangle or strip NonSemantic info even with the strip-guards in place.

Notes

• Build against glslang >= 15.0.0; earlier versions point every DebugFunction at the same file, corrupting name/line correlation.
• Some shaders fail to compile with NonSemantic enabled; since the new flags are independent of -g, this is now a non-issue since builds need to opt in.

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[DannyArends]

Update: I have signed the CLA, let me know if anything else is needed from my side.