Type coercion in SDSL

[ykafia]

Since the SDSL language is being rewritten one question to ask is how do we handle type coercion and inference.

details to note about SPIR-V :

• The built-in types of SPIR-V are the same as GLSL (bool, int, uint, float, double), in order to add (half, short, ushort, byte, sbyte, long, ulong) we should use SPIR-V extensions.
• SPIR-V has some instruction for bit conversions, everything starting by OpConvert, which gives us the power to convert anything to anything conserving bit patterns.
• Type coercion is going to be a little bit more difficult.