Shader Test for glslang and spirv-cross WebMin coverage

[CedricGuillemet]

Many methods are disabled by ENABLE_GLSLANG_WEBMIN and SPIRV_CROSS_ENABLE_WEBMIN. Some of them should be re-enabled.
Make a uber shader or extract Babylon.js shaders to find out what should be re-enabled.
Also, maybe some methods are not disabled by WebMin and should be.

[thomlucc]

Linked to https://github.com/BabylonJS/ThePirateCove/issues/1603 (per @bkaradzic )