test(parser): move over the validator tests and some misc tests to parser

crates/aiken-lang/src/parser/expr/if_else.rs

@@ -49,8 +49,6 @@ pub fn parser<'a>(
 
 #[cfg(test)]
 mod tests {
-    use chumsky::Parser;
-
     use crate::assert_expr;
 
     #[test]

crates/aiken-lang/src/parser/expr/int.rs

@@ -17,8 +17,6 @@ pub fn parser() -> impl Parser<Token, UntypedExpr, Error = ParseError> {
 
 #[cfg(test)]
 mod tests {
-    use chumsky::Parser;
-
     use crate::assert_expr;
 
     #[test]

crates/aiken-lang/src/parser/expr/list.rs

@@ -30,8 +30,6 @@ pub fn parser(
 
 #[cfg(test)]
 mod tests {
-    use chumsky::Parser;
-
     use crate::assert_expr;
 
     #[test]