GEOMESA-281 Create a strategy decider function

refactored to create a Decider that decides on Strategy (attribute index, spatiotemporal index or id index)
Strategy executes the query
this will be the framework upon which more complicated cost analysis of query planning is based
while we're refactoring, it has always seemed a bit confusing that this method is called 'runQuery', since it actually just configures the scanners... maybe we could call it something else?