Add Vulkan validity checks for OpDecorate and OpMemberDecorate in validator

[ghost]

There is a set of non-trivial constraints in SPIR-V & Vulkan specs regarding decorating variables with:

• location & binding qualifiers
• interpolation and patch qualifiers
• offset and alignment

Especially nested interface blocks / structs / arrays need to follow rules defined in "14.1. Shader Input and Output Interfaces" Vulkan spec chapter to get SPIR-V shaders properly "linked" during pipeline creation.

As there are apps (including glslang - KhronosGroup/glslang#269) misusing the decorations it would be good to have these checked in SPIR-V validator.

[dneto0]

Agreed. @umar456 is working on the validator. I believe no Vulkan-specific checks have been implemented yet.

[prideout]

Note that spvValidate currently operates on a single binary, so I think this issue implies that it should actually take a list of binaries in order to validate consistent decorations, e.g. the outs of a VS should match the ins of a FS.

[s-perron]

If there are validation rules that are still not being check, please open a new issue. Many new validation rules have been added already. I'm not sure what specifically is still missing.