IVGCVSW-4874 Provide LayerSupportHandle to frontend users
IVGCVSW-4874 Provide LayerSupportHandle to frontend users

 * Update to use dot operator for IsXXXLayerSupported()
 * Call LayerSupportHandle member funciton to check is Backend Registered

Signed-off-by: Francis Murtagh <e59f6df1240b2b6c2b05aa682b1b9d01b9505720@arm.com>
Change-Id: If0b9876068db8957a8bdb690ad323cd8dce544a4
!armnn:4924

ARM-software/android-nn-driver,ARM-software/android-nn-driver