AthenaServices: Add ThinningCacheTool.

Add ThinningCacheTool, which makes thinning requests available to the I/O layer during output.

Control/AthenaServices/share/ThinningCacheTool_test.ref

+AthenaServices/ThinningCacheTool_test
+
+
+Initializing Gaudi ApplicationMgr using job opts ../share/ThinningCacheTool_test.txt
+JobOptionsSvc        INFO Job options successfully read in from ../share/ThinningCacheTool_test.txt
+ApplicationMgr    SUCCESS 
+====================================================================================================================================
+                                                   Welcome to ApplicationMgr (GaudiCoreSvc v27r1p99)
+                                          running on karma on Thu Oct 24 11:24:46 2019
+====================================================================================================================================
+ApplicationMgr       INFO Application Manager Configured successfully
+EventLoopMgr      WARNING Unable to locate service "EventSelector" 
+EventLoopMgr      WARNING No events will be processed from external input.
+HistogramPersis...WARNING Histograms saving not required.
+ApplicationMgr       INFO Application Manager Initialized successfully
+ApplicationMgr Ready
+test1