[SPARK-16538][SPARKR] fix R call with namespace operator on SparkSession functions

## What changes were proposed in this pull request?

Fix function routing to work with and without namespace operator `SparkR::createDataFrame`

## How was this patch tested?

manual, unit tests

shivaram

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #14195 from felixcheung/rroutedefault.