[turbopack] Add execution tests to demonstrate a bug (vercel#80918)

## Add tests for top level `this` behavior in CJS and ESM modules

### What?
Added two test cases to verify the behavior of `this` in CommonJS and ESM modules:
- CJS test verifies that `this` should be equal to `exports`
- ESM test verifies that `this` should be equal to `globalThis` WHICH IS A BUG, it should be `undefined`

Author: lukesandberg

turbopack/crates/turbopack-tests/tests/execution/turbopack/basic/cjs-this/input/index.js

@@ -0,0 +1,8 @@
+const t = this
+
+it('`this` in cjs should be exports', () => {
+  expect(t).toBe(exports)
+})
+
+// Use a dummy assignment to ensure we are parsed as a cjs module
+exports.something = 'something'

turbopack/crates/turbopack-tests/tests/execution/turbopack/basic/esm-this/input/index.js

@@ -0,0 +1,9 @@
+const t = this
+
+it('`this` in esm should be undefined', () => {
+  // TODO: This is WRONG, it should be undefined
+  expect(t).toBe(globalThis)
+})
+
+// Use a dummy export to ensure this is parsed as an esm module
+export const foo = t