Consolidate sepolicy for twoshay and touchflow targets.

Bug: 187654303
Bug: 187795940
Bug: 198755236
Test: twoshay works on B5, R4, B3, P7; reflector works on O6
Change-Id: I04b98c3b42e886b1900150c175318095e559fa25
diff --git a/input/service_contexts b/input/service_contexts
new file mode 100644
index 0000000..95e70f8
--- /dev/null
+++ b/input/service_contexts
@@ -0,0 +1 @@
+com.google.input.ITouchContextService/default              u:object_r:touch_context_service:s0