With this change we include more detailed error codes in visualization
output. In order to do so we map TGen transfers/streams to TorCtl
STREAM event details based on source ports and unix_ts_end timestamps.
This code reuses some concepts used in metrics-lib.

Implements tpo/metrics/onionperf#34218.

Turns out that stream_info/recvsize contains a string, not an int.

We should include an error_code column in the CSV output, regardless
of whether data contains measurements with an error code or not.
Everything else is just too confusing to whoever processes these
files.

Fixes #40004.

Implements #33257.

Fixes #34261.

Fixes #34216.

We're now including the time that it takes for tor to establish a
circuit and attach a stream in the time to first/last byte.

Implements #34215.

These visualizations are not really useful to us, so we can as well
remove them and all remaining pylab code with it.

As part of this change, output files are being renamed from
tgen.onionperf.viz.yyyy-mm-dd.{csv,pdf} to just
onionperf.viz.yyyy-mm-dd.{csv,pdf}.

Implements #34214.

Previous OnionPerf visualizations were written using PyLab, which is a
relatively low-level visualization library based on matplotlib. PyLab
is the same thing as PyPlot but with some extra shortcuts. However,
using PyLab is discouraged now.

This commit switches all tgen plots to use seaborn, which is a
high-level data visualization library also based on matplotlib. This
commit also uses pandas for underlying data structures in order to
separate data tidying and data visualization.

As a side effect of using pandas, graphed data is now exported to a
.csv file using the same naming scheme as the produced tgen .pdf file.

Implements #33258.

Fixes #29367.

added tor-ctl-logger as monitor mode, parsing analysis mode for
both tgen and tor output, model generation mode for creating
default tgen models, and some util functions