PROV: add testsPassed information
Following triples should be created by the Loki unit tests mechanism (if the PROV plugin is available):
lokievent:{type}_{$page}_{$newRev} loki:testsPassed [ loki:valueBefore "{$metric_val}" ; loki:valueAfter "{$metric_val}" ] ;
Do it the same way as revisionsrater does (triples-related code is placed in the PROV plugin and executed from the revisionsrater).