spirv: Handle SpvOpDecorateId
This operation decorate with an Id instead of a Literal or String. It is used by HlslCounterBufferGOOGLE (provided by SPV_GOOGLE_hlsl_functionality1). Even if we don't do anything with that decoration, we must be able to parse SPIR-V that uses it. Fixes: 891886da "spirv: Add no-op support for VK_GOOGLE_hlsl_functionality1"