[INTERNAL] m.ComboBox: the selected item should be visible
[INTERNAL] m.ComboBox: the selected item should be visible

Ensure that the selected item is visible when the picker
pop-up is opened and the user navigates via keyboard.

Change-Id: I22a21d7a2b13f131dc5117bdf7c05459a4d48762
cschuff/openui5,cschuff/openui5,nzamani/openui5,olirogers/openui5,SQCLabs/openui5,SAP/openui5,nzamani/openui5,SQCLabs/openui5,SAP/openui5,SAP/openui5,SQCLabs/openui5,olirogers/openui5,SAP/openui5,cschuff/openui5,nzamani/openui5,olirogers/openui5