* Check rules from Execution Mode tables, 2.16.2 and the Vulkan
environment spec
* Allows MeshNV execution model with the following execution modes
* LocalSize, LocalSizeId, OutputPoints and OutputVertices
* Done to not break their validation
* Reworked how execution model limitations are checked
* Now OpFunction checks which entry points call it and checks its
registered limitations instead of building a call stack in the entry
point
* New tests
* Moving function to entry point mapping into VState
Fixes https://github.com/KhronosGroup/SPIRV-Tools/issues/1427
Adjusting validation to the new rule:
"Before version 1.3, it is only valid to use this instruction with
TessellationControl, GLCompute, or Kernel execution models.
There is no such restriction starting with version 1.3."
Also fixed wrong version numbers in source/spirv_target_env.cpp.