feat: start creating aiken/builtin module

examples/sample/src/sample/syntax.ak

@@ -1,7 +1,13 @@
+use aiken/builtin.{addInteger}
+
 pub type ScriptContext {
   idk: Int
 }
 
 pub fn append(a: ByteArray, b: ByteArray) -> ByteArray {
   todo
+}
+
+pub fn add(a, b) {
+  addInteger(a, b)
 }