Introducing a trait for running compares.

This should enable us to invoke compares without needing a reference ast node type.

src/wasm_test/elisp_compare.rs

@@ -0,0 +1,10 @@
+use super::compare::WasmDiffEntry;
+use crate::compare::Token;
+
+pub trait WasmElispCompare<'s, 'p> {
+    fn compare_ast_node<'b>(
+        &'p self,
+        source: &'s str,
+        emacs: &'b Token<'s>,
+    ) -> Result<WasmDiffEntry<'b, 's>, Box<dyn std::error::Error>>;
+}