feat: add hydra source (#823)
To run, first start the hydra demo:
```bash
cd hydra/demo
./prepare-devnet.sh
docker compose up -d cardano-node
./seed-devnet.sh
docker compose up -d hydra-node-{1,2,3}
```
Then, in this repositroy, run:
```bash
cargo run --features hydra daemon --config examples/hydra/daemon.toml
```
Tests can be run with `cargo test --features hydra`.
This commit is squashed from many intermediate commits and PRs.
Co-authored-by: Johannes Lund <[email protected]>