feat: add opcc slashing event

[parketh]

Summary

This is a PR to update the BTC Slasher program to support and handle OP stack consumer chain slashing events.

It accompanies babylonlabs-io/babylon-contract#92.

Test plan

Before running integration tests, I needed to set DOCKER_HOST:

export DOCKER_HOST="unix:///Users/parkyeung/.docker/run/docker.sock"

To run tests:

# unit tests
make test

# integration tests
make test-e2e

[lesterli]

it should be #139

[SebastianElvis]

Thanks!

@KonradStaniec Is it okay that for the main branch we have this piece of code for integration?

[KonradStaniec]

@KonradStaniec Is it okay that for the main branch we have this piece of code for integration?

This seems like small piece of code so it should be fine 👍

Also e2e tests are passing so it should it seems that it is possible to subscribe to the messages that do not exists yet on Babylon (MsgEquivocationEvidence)