Material path resolver rewrite to be more robust

[Glorou]

There was an issue where non-vanilla material names would cause this function to a) fault because the material string was too short and would cause one of the functions to break, or b) return garbage since they dont conform to vanilla naming conventions (most of the time). This rewrite uses regex to check for the syntax safely in one regex match. I confirmed the function works using Penumbra and passing various material names and monitoring behavior.