Reduce ubershader size by reusing structs for different techniques if identical

[myluki2000]

Currently, for each permutation of ubershader arguments, a separate struct is generated. If the struct's structure is only different for 1 or 2 ubershader arguments, and identical no matter the value of the others, this results in a lot of duplicate structs. This could be optimized by analyzing generated structs' structure and if it is identical between different ubershader permutations, reusing the already existing structs instead of generating new ones