[INTERNAL] mvc/XMLView: aggregations on XML root level
[INTERNAL] mvc/XMLView: aggregations on XML root level

- aggregations specified on XMLViews on root level cannot be handled
  properly
- adapted constructor and factory documentation accordingly

Change-Id: Ibd11ba562563003e29bce5e81eac4750227947cd
BCP: 1780052667

olirogers/openui5,SAP/openui5,SAP/openui5,nzamani/openui5,SAP/openui5,nzamani/openui5,nzamani/openui5,SQCLabs/openui5,SAP/openui5,SQCLabs/openui5,SQCLabs/openui5,olirogers/openui5,cschuff/openui5,cschuff/openui5,olirogers/openui5,cschuff/openui5