Compile each static shader using shaderc to Spir-V binaries.
The main goal is to make sure that the GLSL created using ShaderCreateInfo and able to compile to Spir-V.
For the second stage a correct pipeline needs to be created and some shader would need more
adjustments (push constants size).
With this patch future changes to GLSL sources can already be checked against vulkan, without the
backend finished.
Mechanism has been tested using MacOS and MoltenVK. For other OS, we should finetune CMake
files to find the right location to shaderc.
```
************************************************************
*** Build Fri 2 Dec 2022 12:06:02 CET
************************************************************
[5/7] Generating shader_baked.hh
Shader Test compilation result: 365 / 365 passed (skipped 116 for compatibility reasons)
OpenGL backend shader compilation succeeded.
Shader Test compilation result: 481 / 481 passed
Vulkan backend shader compilation succeeded.
```
# TODO #
[ ] Remove the temp hack to ignore the GPU_batch_init.