[INTERNAL] sap.tnt.BoxContainer: Example page improvements
[INTERNAL] sap.tnt.BoxContainer: Example page improvements

* Splitted the samples in categories by using IconTabBar
* Added multiple real use cases provided by designers

JIRA: BGSOFUIRODOPI-1481
Change-Id: Ia075d3b3518311712fdb2b4696b026af224cda24

cschuff/openui5,SAP/openui5,cschuff/openui5,SAP/openui5,SAP/openui5,SAP/openui5,cschuff/openui5