YUL tree visitor interface (#369)

- Implement the visitor interface. This simplifies working with the AST,
for example transformations into other IRs or collecting and analyzing
various statistics.
- Switch the explorer to use the visitor interface.
- Add the reciprocal function name conversion for function names.
- Some drive-by cosmetic fixes.

---------

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

crates/yul/src/parser/statement/code.rs

@@ -13,6 +13,8 @@ use crate::lexer::token::Token;
 use crate::lexer::Lexer;
 use crate::parser::error::Error as ParserError;
 use crate::parser::statement::block::Block;
+use crate::visitor::AstNode;
+use crate::visitor::AstVisitor;
 
 /// The YUL code entity, which is the first block of the object.
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Eq)]
@@ -66,6 +68,20 @@ where
     }
 }
 
+impl AstNode for Code {
+    fn accept(&self, ast_visitor: &mut impl AstVisitor) {
+        ast_visitor.visit_code(self);
+    }
+
+    fn visit_children(&self, ast_visitor: &mut impl AstVisitor) {
+        self.block.accept(ast_visitor);
+    }
+
+    fn location(&self) -> Location {
+        self.location
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::lexer::token::location::Location;