Rename the coins folder to networks

Ethereum isn't a coin. It's a network.

Resolves #357.

networks/ethereum/src/tests/abi/mod.rs

@@ -0,0 +1,13 @@
+use alloy_sol_types::sol;
+
+#[rustfmt::skip]
+#[allow(warnings)]
+#[allow(needless_pass_by_value)]
+#[allow(clippy::all)]
+#[allow(clippy::ignored_unit_patterns)]
+#[allow(clippy::redundant_closure_for_method_calls)]
+mod schnorr_container {
+  use super::*;
+  sol!("src/tests/contracts/Schnorr.sol");
+}
+pub(crate) use schnorr_container::TestSchnorr as schnorr;