Refactor package

[p-gw]

This pull request refactors the whole package.

Major changes:

• Use different structs for frequentist and bayesian models
• Use implementations from ItemResponseFunctions.jl (closes Implement ItemResponseFunctions.jl #59)
• Use person parameter estimation from PersonParameters.jl (closes Implement PersonParameters.jl #60)
• General changes to the package structure to make it more easily extendable
• Explicit function imports

TODO

• Deal with namespace clashes from Turing and PersonParameters (MLE, MAP)
• Fix unit tests
• Require julia 1.10
• Let the algorithm determine the output struct
• Update to AbstractItemResponseModels 0.3
• Update to ItemResponseFunctions 0.2
• Update compat