Revert "added always-throwing implementation for ScalarAccessor::readAsync()"

This reverts commit 4f2b35be.

Was actually used and tested.

include/ScalarAccessor.h

@@ -68,11 +68,6 @@ namespace ChimeraTK {
       return dataLoss;
     }
 
-    TransferFuture readAsync() {
-      throw ChimeraTK::logic_error("ScalarAccessor::readAsync() is currently not "
-                                   "supported by ApplicationCore!");
-    }
-
    protected:
     friend class InversionOfControlAccessor<ScalarAccessor<UserType>>;