non evaluation-phase function equivalents required

[ivakegg]

Users can currently apply a regex to a field (e.g. FIELD =~ 'regex' or FIELD:/regex/) . Users can also apply a regex with an evaluation phase filter function (filter:includeRegex(FIELD, 'regex') or #INCLUDE(FIELD,regex)). On functions we can apply other operations such as size (see FunctionalSet) (e.g. filter:getAllMatches(FIELD, 'regex').size() == 2). However we do not have a regex matching function that can be applied efficiently to a index-only field such (given we implement #1295) such that additional operations can be applied. Recommend creating a new bucket of functions like those in EvaluationPhaseFilterFunctions that so the same things except that the index queries are generated correctly (via the function descriptor).