Add Profiles for Library, Measure and MeasureReport

[alexanderkiel]

We need profiles for Library, Measure and MeasureReport because we should make clear what features of the whole Quality Reporting module we like to use.

There is already an whole IG about Quality Reporting the Quality Measure STU2 for FHIR R4 IG. We should examine what we like to use from it and what not.

[alexanderkiel]

One observation I made from Quality Measure STU2 for FHIR R4 IG is in section 3.4.8 Stratification they constrain stratifier expressions to return only boolean values for patient based measures.

In the example of our age classes, it would mean, we need one stratifier for each age class and the MeasureReport would contain two strata, one with the value true and one with the value false.