RavenDB-2478: fixed some problems with the metrics unique ids and measuring of time
removed all time meter metrics from the system (left only time histograms)
some code refactoring:
unified all metric, histrogram conversions inside MetricExtension.cs,
moved SqlReplicaitonMtricsCounterManager to dedicated file,
access to sqlreplication metrics is now only from /debug/sql-replication-stats