Added ScrollBar Indicator minimum size and padding properties

Added ScrollBar Indicator minimum size and padding properties

These 3 properties are floats, and can be set as follows (these are examples only):
scrollBar.SetProperty( ScrollBar::Property::INDICATOR_MINIMUM_HEIGHT, 20 );
scrollBar.SetProperty( ScrollBar::Property::INDICATOR_START_PADDING, 10 );
scrollBar.SetProperty( ScrollBar::Property::INDICATOR_END_PADDING, 10 );

Note: With a Vertical ScrollBar Direction: START and END padding properties refer to Top and Bottom respectively.

The defaults for all 3 properties is 0.

Change-Id: I79d9b28f36cca29a0e9115839cc5a5c70691bf65