Add flag logical dimensions backed by tag physical dimension support to Fili

[michael-mclawhorn]

It would be convenient to have a way to use a druid multivalue as a boolean tag.

One way this has been implemented is by having two dimension columns, one a comma delimited list of values, one a multivalue druid dimension.

As an implementation strategy we should have a TagDimension which has references to both the multivalue and the string versions of the dimension. Grouping can be accomplished by using extraction functions to turn the string version into 'Yes' and 'No' values based on the flag presence.

Filtering, for efficiency, should be based on the multivalue dimension. This will require a Tag Dimension Aware ApiFilter generator. It should transform

flagDimension|key-eq[Yes] into tagDimension|multiValueColumn-eq[tagValue]