[FIX] sap.m.ObjectAttribute: Keyboard handling

If property active is set to true, the ObjectAttribute will react on
Space and Enter keys which trigger the press event. Added qUnit tests to
cover the fix and explored sample to demonstrate the use-case.

Change-Id: Iaa7ba06f5cb811d35ec32f1376ac973de1098b8a
CSS: 0120031469 0000671382 2014
Merge "[FIX] sap.m.ObjectAttribute: Keyboard handling"