IVGCVSW-3561 Fix the linker issues of the test shared objects in

IVGCVSW-3561 Fix the linker issues of the test shared objects in
the Android builds

 * Changed the test libs from SHARED to MODULE
 * Added IBackendInternal.cpp to separate the default
   implementation of OptimizeSubgraphView from the header file
 * Linked the modules against armnn to get the missing symbols
 * Renamed the test modules to avoid name clashing in the CI system
 * Moved the test shared objects to separate folders to keep the
   filesystem tidy

Change-Id: I987c56d2d66bdb86f7b391a83c602d0dadf4c674
Signed-off-by: Matteo Martincigh <matteo.martincigh@arm.com>