feat(bidcollect): Make top-bid websocket stream generic (and also subscribe to Aestus)

[metachris]

📝 Summary

• Make top-bid websocket stream usable for any URL (not only Ultrasound)
• Add Aestus top-bid websocket stream

⛱ Motivation and Context

Before, the top-bid websocket stream was closely tied to Ultrasound relay only, and it wasn't possible to subscribe to other sources.

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✅ I have run these commands

• [x] make lint
• [x] make test
• [x] go mod tidy