Emerge Yul recompiler (#1)

Provide a modified (and incomplete) version of ZKSync zksolc that can compile the most basic contracts

crates/solidity/src/solc/pipeline.rs

@@ -0,0 +1,32 @@
+//!
+//! The Solidity compiler pipeline type.
+//!
+
+use crate::solc::version::Version as SolcVersion;
+use crate::solc::Compiler as SolcCompiler;
+
+///
+/// The Solidity compiler pipeline type.
+///
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+#[allow(non_camel_case_types)]
+#[allow(clippy::upper_case_acronyms)]
+pub enum Pipeline {
+    /// The Yul IR.
+    Yul,
+    /// The EVM legacy assembly IR.
+    EVMLA,
+}
+
+impl Pipeline {
+    ///
+    /// We always use EVMLA for Solidity <=0.7, or if the user does not want to compile via Yul.
+    ///
+    pub fn new(solc_version: &SolcVersion, force_evmla: bool) -> Self {
+        if solc_version.default < SolcCompiler::FIRST_YUL_VERSION || force_evmla {
+            Self::EVMLA
+        } else {
+            Self::Yul
+        }
+    }
+}