[FIX] sap.m.Input suggestionItemSelected event handling improvement

The suggestionItemSelected event is now fired before the update of the
DOM item and the setting of the input value.

This allows to process this event by application hooks and suggestion
providers before the input field is updated by the control.

If the value of the input field is changed in the registered event
handler, the value of the selected item is ignored and the custom value
is used instead.

(cherry picked from commit 1b857fffd1a9a8fb156894e4b1cbd26f549ba226)

BCP: 1482017037
Change-Id: If6bd186ead4343fa3a561d7f36e709c2a82d88df
CR-Id: 012006153200015173222014
Merge "[FIX] sap.m.Input suggestionItemSelected event handling improvement" into rel-1.26