fix: Limit calls to subscribe()

[adityapk00]

Motivation

The subscribe() RPC is a long-lived one, which causes excessive resource consumption for every open connection. Limit these to 4 per IP and 4096 total per Node.

Change Summary

• Limit subscribe() to 4 per IP
• Limit 4096 total
• Tests

Merge Checklist

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• PR title adheres to the conventional commits standard
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PR-Codex overview

This PR focuses on limiting the number of simultaneous subscribe() streams by IP address in the Hubble app.

Detailed summary

• Added extractIPAddress function to extract the IP part from "ip:port"
• Modified checkNodeAddrs function to check the IP address to bind to and the combined IP, transport, and port multiaddr
• Added SUBSCRIBE_PERIP_LIMIT and SUBSCRIBE_GLOBAL_LIMIT constants in server.ts
• Added IpConnectionLimiter class to limit the number of simultaneous connections by IP address
• Modified Server class to use IpConnectionLimiter for rate limiting in subscribe method
• Added clearRateLimiters method in Server class to clear rate limiters
• Updated tests in eventService.test.ts and server.ts

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[changeset-bot]

🦋 Changeset detected

Latest commit: c5cc599

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@farcaster/hubble	Patch

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Name	Status	Preview	Comments	Updated (UTC)
hub-monorepo	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jul 31, 2023 0:51am

[codecov]

Codecov Report

Patch coverage: 75.47% and project coverage change: -0.07% ⚠️

Comparison is base (eae1ba8) 69.38% compared to head (c5cc599) 69.31%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1197      +/-   ##
==========================================
- Coverage   69.38%   69.31%   -0.07%     
==========================================
  Files          84       84              
  Lines        7428     7473      +45     
  Branches     1604     1614      +10     
==========================================
+ Hits         5154     5180      +26     
- Misses       2123     2141      +18     
- Partials      151      152       +1     

Files Changed	Coverage Δ
apps/hubble/src/utils/p2p.ts	63.52% <71.42%> (+0.70%)	⬆️
apps/hubble/src/rpc/server.ts	74.47% <76.08%> (-1.19%)	⬇️

... and 1 file with indirect coverage changes

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