Adding Selection Markers to TextField

* Selection Markers if specified in json style file whill add a upper left image and upper right image to the selection handle.
 They can be on the same level as the text and stretch to it's height.

* Image Handle Properties for decorations changed from string to Map as string did not work. Control used MAP for background-image.

* Updated TCT cases for testing Handle Images

Change-Id: I2df31baa4a1c6fe5a34b437532c46393b4d6aee3
Signed-off-by: Agnelo Vaz <agnelo.vaz@samsung.com>