Import the [[ https://github.com/rust-bitcoin/rust-secp256k1 | rust-secp256k1 ]] repository, and apply the following modifications:
- Removed the secp256k1 library imported from bitcoin-core, as well as all the vendoring code
- Use our secp256k1 library of the monorepo
- Add `schnorrabc`, which are the Schnorr signatures used by ABC. These are distinct from the x-only pubkey BIP340 signatures from BTC, but not removed here, to allow for easier backports.
- Removed a lot of GitHub CI related files. Sophisticated CI can be added later. NB: This also disables most of the tests, but those are not very simple to set up. For now, we only do the integration tests with ecash-lib and ecash-agora.
- Adapt the Rust workspace structure to our workspace.
- Reformat everything with our formatting rules.