implement Router.sol and associated functions (#92)

* start Router contract

* use calldata for function args

* var name changes

* start testing router contract

* test with and without abi.encode

* cleanup

* why tf isn't tests/utils working

* cleanup tests

* remove unused files

* wip

* fix router contract and tests, add set/update public keys funcs

* impl some Froms

* make execute non-reentrant

* cleanup

* update Router to use ReentrancyGuard

* update contract to use errors, use bitfield in Executed event, minor other fixes

* wip

* fix build issues from merge, tests ok

* Router.sol cleanup

* cleanup, uncomment stuff

* bump ethers.rs version to latest

* make contract functions take generic middleware

* update build script to assert no compiler errors

* hardcode pubkey parity into contract, update tests

* Polish coins/ethereum in various ways

---------

Co-authored-by: Luke Parker <lukeparker5132@gmail.com>

coins/ethereum/src/lib.rs

@@ -1,2 +1,16 @@
-pub mod contract;
+use thiserror::Error;
+
 pub mod crypto;
+
+pub(crate) mod abi;
+pub mod schnorr;
+pub mod router;
+
+#[cfg(test)]
+mod tests;
+
+#[derive(Error, Debug)]
+pub enum Error {
+  #[error("failed to verify Schnorr signature")]
+  InvalidSignature,
+}