Make FilterReporters central and properly dual-use

Make FilterReporter and FilterReporterParams central with minor modifications:

• reduce the amount of messaging to avoid unneeded slowdown
• make filter key configurable and separate from algorithm name
• move out of EL namespace

I also added several tests for it and a new AllExecutedEventsCounterAlg. Initial new-style config also added.

/cc @tsulaia @krumnack