Add a get_hist_total method wrapper

[gvegayon]

• [ ] Create a method/function to wrap the method DataBase.get_hist_total().
• [ ] The outputs should be stored in a dictionary with three three values date, state, and counts; each of them a numpy array.
• [ ] Create a test making sure this runs, i.e., run a simulation, call the function, and check the lengths of the elements (all three should match).
• [ ] Add an example in the README.qmd that uses the functions and plots the counts of each time series (suscept, infec, rec) using matplotlib.