Add accumulator conditions to :condition-matches in session inspection

[WilliamParker]

This is similar to #289 but for accumulator conditions rather than negation conditions. So, for example, if we have a rule like

(defrule min-temp-and-windspeed
    [?min-temp (acc/min :temperature) <- Temperature (some-predicate this)]
    [?min-wind (acc/min :windspeed) <- WindSpeed (some-predicate-2 this)]
   =>
  (insert (->ColdAndWindy ?min-temp ?min-wind)))

we'd be able to find Temperature facts matching some-predicate by looking at the :condition-matches. We'd also be able to find WindSpeed facts matching some-predicate-2 if the predicate did not depend on bindings from previous conditions. As in general for the :condition-matches, we'd be able to find these matches regardless of whether the rule fired, so even if there were, say, no WindSpeed facts we could still inspect on the Temperature condition.