Added UseFocusIndicator API to devel keyboard-focus-manager

Added UseFocusIndicator API to devel keyboard-focus-manager

Added UseFocusIndicator API to devel keyboard-focus-manager.

Some developers want to use other way to indicate focus state instead of using focus indicator.
In this case, currently they use work-around which is setting transparent actor as focus indicator.

For convenience, support UseFocusIndicator API.

If user sets state to false, focus indicator will disapear immediately
and not be shown until setting state to true.

Change-Id: I0678f56e17e76751fe6a365b2d565f7b592c6d36
Signed-off-by: minho.sun <minho.sun@samsung.com>