feat: support negation of int

* add unary op
* parse, typecheck, and code gen it
* express boolean not as unary op as well, previously called negate

Co-authored-by: rvcas <x@rvcas.dev>

crates/aiken-lang/src/parser/lexer.rs

@@ -9,13 +9,9 @@ use super::{error::ParseError, token::Token};
 pub fn lexer() -> impl Parser<char, Vec<(Token, Span)>, Error = ParseError> {
     let int = choice((
         text::int(10),
-        text::int(16),
         just("-")
             .ignore_then(text::int(10))
             .map(|value: String| format!("-{}", &value)),
-        just("-")
-            .ignore_then(text::int(16))
-            .map(|value: String| format!("-{}", &value)),
     ))
     .map(|value| Token::Int { value });