Adding a metric for the network time value itself should make it
possible to observe it stopping or growing slowly as compared to
realtime when Zeek isn't able to keep up.
Also, modify the telemetry/log.zeek test to include misc/stats and
log at a higher frequency with a more interesting pcap.
Adds base/frameworks/telemetry with wrappers around telemetry.bif
and updates telemetry/Manager to support collecting metrics from
script land.
Add policy/frameworks/telemetry/log for logging of metrics data
into a new telemetry.log and telemetry_histogram.log and add into
local.zeek by default.
