Evaluate using roflcoptor as Tor control port filter

Originally created by @sajolida on #11542 (Redmine)

It seems to be used by Subgraph and the successor of or-ctl-sieve, which I mentioned in #6742 (comment 103978).

If it matches our requirements and is likely to be maintained, maybe we should replace our custom control port filter with this.

Edited May 15, 2020 by sajolida

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