TMSS-770: Update get_subs_and_durations_from_project by splitting SUBs in Prio A,B and switching to observed_durations

TMSS-857: Update distinction between successful/failed observations for the reporting (workflow flag)

TMSS-745: fixed inheritance for Meta class in various models. Otherwise base Meta properties (like constraints) are missed.

TMSS-745: pulled out common version number code for templates, and applied it to SchedulingUnitObservingStrategyTemplate as well.

TMSS-745: extract scheduling_constraints_doc and scheduling_constraints_template from submitted template and use it.

TMSS-745: handle trigger submission in one transaction. If anything fails, the whole trigger is discarded.

TMSS-745: use the new functionality from the refactored strategy templates to construct a valid trigger doc, and submit it to tmss

TMSS-745: added various convenience endpoints on the SchedulingUnitObservingStrategyTemplate to get various versions of the template document: plain, complete_with_all_defaults, just_with_the_parameters. Can be used to construct json documents to upload as schedulingunitdraft or for triggers

TMSS-745: added subdict_of_pointer_items method to extract a subdict given a list of json-pointer-paths