GEOMESA-418 Time-enabled layer previews are not handled optimally

Recognizing binary inequality filters involving canonical time variable as temporal filters and handling them like before/after.
It is also legal in ECQL to have the literal first, e.g. 3 < dtg (vs dtg > 3). See https://github.com/locationtech/geomesa/blob/accumulo1.5.x/1.x/geomesa-core/src/main/scala/org/locationtech/geomesa/core/index/AttributeIdxStrategy.scala#L300 and associated code.