[FEATURE] sap.m.ObjectAttribute: Screen reader support implemented

If the ObjectAttribute is not active it will be read as plain text,
otherwise it will be read as a link. Added a unit test for the latter
case.

Change-Id: Ic7d2745368e0291328d91d5d7f49048555741a63
Merge "[FEATURE] sap.m.ObjectAttribute: Screen reader support implemented"