implement a simple statsd logger (closes #5488711)
and add a few timing probes on:
- etwist.server.CubicWebRootResource.render_request()
- server.querier.QuerierHelper.execute()
- server.sources.native.NativeSQLSource:
- sqlexec()
- compile_rql()
- authenticate()
- doexec()
- doexecmany()
as well as a pair of counters on server.querier.QuerierHelper cache (hit/miss).