Better testing infrastructure; Initial exports/imports/re-exports

tests/compiler/export.ts

@@ -0,0 +1,15 @@
+export function add(a: i32, b: i32): i32 {
+  return a + b;
+}
+
+function sub(a: i32, b: i32): i32 {
+  return a - b;
+}
+
+export { sub as renamed_sub };
+
+export let a: i32 = 1;
+
+let b: i32 = 2;
+
+export { b as renamed_b };