feat: add peer-ids to blacklist using sysctl

[luislhl]

Motivation

An easy way to dynamically add peer-ids to our blacklist was needed to block some misbehaving peers.

Although we have the /p2p/netfilter endpoint built in #484, it's more generic and more low level, requiring the user to know about chain names, rule names, keep the uuid of created rules when deleting them, etc.

The sysctl command aims to be a simpler/quicker way to add peer-ids to the blacklist, and it works well with the current p2p.kill_connection sysctl command (because neither this new command nor the existing endpoint will disconnect the peer-ids after adding to the blacklist, in case it's connected already).

Acceptance Criteria

• New sysctl commands p2p.blacklist.add_peers, p2p.blacklist.remove_peers and p2p.blacklist.list_peers
• Validate that the peer-ids are in a valid format
• Keep track of the rule uuid so that user can remove them later using only the peer-id
• These rules will be kept in memory and be specific for one fullnode, so they won't persist throughout the network. The user could use the --peer-id-blacklist cli arg to make them persist in each needed fullnode.

TODO

• Update docs/SOPs with the new command
• Test

Checklist

• If you are requesting a merge into master, confirm this code is production-ready and can be included in future releases as soon as it gets merged

[github-actions]

Bencher Report

Branch	feat/sysctl/peer-id-blacklist
Testbed	ubuntu-22.04

Click to view all benchmark results

Benchmark	Latency	Benchmark Result minutes (m) (Result Δ%)	Lower Boundary minutes (m) (Limit %)	Upper Boundary minutes (m) (Limit %)
sync-v2 (up to 20000 blocks)	📈 view plot 🚷 view threshold	1.68 m (-1.83%) Baseline: 1.71 m	1.54 m (91.67%)	2.06 m (81.81%)

🐰 View full continuous benchmarking report in Bencher

[jansegre]

#1544 seems to touch on many similar functionality (although #1544 does not implement blacklisting), I think this PR could be rebased to #1544 and implement blacklisting using that structure