Resolve "[Collection] Issue for ID, refType and refID inconsistencies"

Closes #131

Element / Type	ID	refId	refType	Comment	Implemented
items	X			Majority voted against the change	❌
respPerson	X			We don't need refType if we implement "role" (#134)	✅
statementMetadataType	X	X	X	refId should be an attribute here to stay consistent	✅
usedMethodType	X		X		✅
softwareType	X		X		✅
measuringEquipmentType	X		X		✅
measurementResultType	X	X	X		✅
dataType	X	X	X	Should not be implemented, because resultType already has these	❌
listType	X	X	X		✅
formulaType	X				✅
xmlType	X				✅