Nested sampling with FitPlanck

[tomasstolker]

• Bug fix of for loop indices in likelihood function with the use of duplicate filter names.
• Type hints and type checks added in FitPlanck.
• Prior added to FitPlanck when multiple blackbody components are fitted to enforce the temperature and radii to decrease and increase, respectively.
• Added run_multinest to FitPlanck to use nested sampling for the parameter estimation, complementing MCMC with run_mcmc.
• The inc_luminosity parameters also supports results from FitPlanck with multiple blackbody components.
• The luminosity is added to the ModelBox from ReadPlanck.get_spectrum.
• Updated axis labels for plots.