TMSS-250: add endpoint for target rise and set, and add sky constraint logic that uses it

...ces/scheduling/lib/constraints/template_constraints_v1.py

SAS/TMSS/services/scheduling/test/t_dynamic_scheduling.py

SAS/TMSS/src/tmss/tmssapp/conversions.py

SAS/TMSS/src/tmss/tmssapp/views.py

SAS/TMSS/src/tmss/urls.py

SAS/TMSS/test/t_conversions.py