resolc crate (#328)

- Factor the YUL crate out of `revive-solidity`.
- `revive-solidity` is in reality not a Solidity implementation but the
revive solidity compiler driver (`resolc`). By renaming we not only get
this straight but also a binary with the same name as the crate which
should be less confusing.

---------

Signed-off-by: Cyrill Leutwiler <bigcyrill@hotmail.com>

crates/resolc/src/tests/ir_artifacts.rs

@@ -0,0 +1,45 @@
+//! The Solidity compiler unit tests for IR artifacts.
+//! The tests check if the IR artifacts are kept in the final output.
+
+#![cfg(test)]
+
+use std::collections::BTreeMap;
+
+#[test]
+fn yul() {
+    let source_code = r#"
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+contract Test {
+    function main() public view returns (uint) {
+        return 42;
+    }
+}
+    "#;
+
+    let mut sources = BTreeMap::new();
+    sources.insert("test.sol".to_owned(), source_code.to_owned());
+
+    let build = super::build_solidity(
+        sources,
+        BTreeMap::new(),
+        None,
+        revive_llvm_context::OptimizerSettings::cycles(),
+    )
+    .expect("Test failure");
+
+    assert!(
+        build
+            .contracts
+            .as_ref()
+            .expect("Always exists")
+            .get("test.sol")
+            .expect("Always exists")
+            .get("Test")
+            .expect("Always exists")
+            .ir_optimized
+            .is_some(),
+        "Yul IR is missing"
+    );
+}