[ENHANCEMENT] Use `Moshi.@match` instead of `MLStyle.@match`

[mtfishman]

Currently we are using MLStyle.@match for pattern matching to help write macros. I think we should replace it with Moshi.@match, which is very similar and Moshi.jl is meant to be a replacement for MLStyle.jl. I tried Moshi.@match at first and hit some problems but I may have just been using it wrong.