Implement new excess non-AIDS mortality among PLHIV implemented in
Spectrum 6.38 for 2025 UNAIDS HIV estimates.

Spectrum 6.38 implements rates of non-AIDS excess mortality by sex,
age group, CD4 category and ART status. By default these mortality rates
are applied in concentrated epidemic countries and defaulted to zero in
African HIV epidemic settings.

Spectrum outputs for non-AIDS deaths among PLHIV in AIM include non-AIDS
excess deaths. EPP-ASM deaths outputs are updated accordingly.

To ensure backward compatibility, excess non-AIDS mortality are initialized
to 0.0 and replaced with values read from Spectrum if the relevant values
exist in the .DP file.

simmod() updated to incorporate excess non-AIDS mortality among PLHIV.
Internally new model parameters arrays cd4_nonaids_excess_mort and
art_nonaids_excess_mort follow the same dimensions and stratification
of cd4_mort and art_mort arrays. These represent expansions of the
arrays saved in Spectrum-AIM, to all age groups and ART duration categories,
consistent with handling of the cd4_mort and art_mort arrays.

Fix bug in R version for end-year net migration in first year of ART eligibility