Rewrite integration test harness ensuring interop with CLN, Eclair, and LND

While we have integration tests with CLN and LND, they so far cover only very basic flows.

We should create a more sophisticated test harness (probably using `proptest`?) that also adds Eclair interop coverage covers more and more error prone scenarios, such as:

a) peer disconnection and reconnection
b) splicing
c) channel closing
d) fee rate disagreements


etc.