This includes adding property 'OnionPerfSources' and renaming
some markers properly.  In addition, all camel-case occurrences
of 'OnionPerf' have a capitalized 'P' now.

Part of task-21759.

Implements task20516.

Implements task20515.

Implements #22833.

This patch reverts a path change made in 8767c73d.

Fixes #22754.

Implements part of #21551.

Implements #22652.

Similar to other statistics lines, there's nothing particular
sensitive in these new padding-counts lines that would reveal the
bridge IP address or location.  We can simply copy them over.

Implements #22216.

We recently switched to downloading .tpf files from OnionPerf hosts,
and we ran out of functioning Torperf hosts, so let's remove the code
for downloading and merging Torperf files.  Part of #21272.

Implements #21272.

Implements #21535.

Fixes #21443.

Use try-with-resources to prevent this.

Implements task-21195.

Fixes #21143.