[Refactor]: Add NormalLPDF child class

[Andrea-Havron-NOAA]

Refactor request

This will replace the Dnorm class in tmb_distributions.hpp

• [x] Add the following class members:

  • [x] fims::Vector<Type> log_sd
  • [x] fims::Vector<Type> sd
  • [x] fims::Vector<Type> nll

• [x] Add the member function: evaluate()

  • [x] loops over observed_values and calculates the negative log density - record in vector so user can access observation level log density calculations
  • [ ] add if (!containsNA) conditional
  • [x] returns the sum of the negative log density vector
  • [x] within simulate_flag, include a simulate function and report wrapper for oberved_values

[Andrea-Havron-NOAA]

move add if (!containsNA) conditional to separate issue

[Andrea-Havron-NOAA]

close with PR#610