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/mod.rs

@@ -0,0 +1,14 @@
+//! The Solidity compiler unit tests.
+
+#![cfg(test)]
+
+mod factory_dependency;
+mod ir_artifacts;
+mod libraries;
+mod messages;
+mod optimizer;
+mod remappings;
+mod runtime_code;
+mod unsupported_opcodes;
+
+pub(crate) use super::test_utils::*;