Add a generic lightning client which can sync from any node

[TheBlueMatt]

This is kinda hacked up, is missing some stuff, and isn't tested, just opening to show what this would look like and get feedback on if this is worth doing.

Reasons to consider this:

• Doesn't require a local lightning node - just point this at one (or more) lightning nodes' P2P ports and it'll fetch the graph
• Gives mempool lower-level access to lightning gossip data, with raw messages locally in-memory destructured into Javascript (WASM) classes
• Could remove the existing multi-implementation API, though I'm not sure there's any reason to do that unless there's some additional info we want that isn't available reliably in all RPCs (Show lightning channel disable bit (and maybe some historical info) #4117 maybe? though its probably available)

Reasons not to do this:

• Mostly performance - syncing the lightning gossip data requires verifying that the gossip data actually matches the chain, which requires quite some traffic to the blockchain API backend (not yet fully implemented, but you can see roughly what it looks like)
• Takes on a chunky WASM blob dependency.

[cla-bot]

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[cla-bot]

Thanks for your contribution to The Mempool Open Source Project. We require all contributors to agree to our Contributor License Agreement and don't seem to have one for you on file. Please see the instructions in CONTRIBUTING.md to proceed with this pull request.

[TheBlueMatt]

Wat, bro, there is one in master, do you not like its format?