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/lexer/token/lexeme/literal/mod.rs

@@ -27,7 +27,7 @@ impl std::fmt::Display for Literal {
         match self {
             Self::Boolean(inner) => write!(f, "{inner}"),
             Self::Integer(inner) => write!(f, "{inner}"),
-            Self::String(inner) => write!(f, "{inner}"),
+            Self::String(inner) => write!(f, "\"{inner}\""),
         }
     }
 }