GEOMESA-101 Optimize geometry only queries in iterator

Adds an iterator that runs in place of both the SpatioTemporalIntersectingIterator and the SimpleFeatureFilteringIterator.  This iterator is used in special situations where the ECQL query can be fully re-written in terms of a polygon and interval AND a transform is defined that only selects the index attributes. 
  
Does the following work (and read better)?

```scala
for {
   transformOpt <- Option(query.getHints.get(TRANSFORMS))
   transform       <- transformOpt.asInstanceOf[String]
   _                    <- cfg.addOption(GEOMESA_ITERATORS_TRANSFORM, transform)
   sfType           <- transformedSimpleFeatureType(query)
  _                     <- cfg.addOption(...)
} yield Unit
```