Split pattern parser into individual modules.

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

@@ -0,0 +1,16 @@
+use chumsky::prelude::*;
+
+use crate::{
+    ast::UntypedPattern,
+    parser::{error::ParseError, token::Token},
+};
+
+pub fn parser() -> impl Parser<Token, UntypedPattern, Error = ParseError> {
+    select! {Token::Int {value, base} => (value, base)}.map_with_span(|(value, base), location| {
+        UntypedPattern::Int {
+            location,
+            value,
+            base,
+        }
+    })
+}