Add new acceptance test scenario (009)

Note: the problem is only present when importing a builtin explicitly.
  When using a qualified import, it compiles fine.

  ```
  Error:
    × Main thread panicked.
    ├─▶ at crates/lang/src/uplc.rs:3264:35
    ╰─▶ called `Option::unwrap()` on a `None` value
    help: set the `RUST_BACKTRACE=1` environment variable to display a backtrace.
  ```

examples/acceptance_tests/009/aiken.toml

@@ -0,0 +1,2 @@
+name = "acceptance_test_009"
+version = "0.0.0"

examples/acceptance_tests/009/lib/test.ak

@@ -0,0 +1,9 @@
+use aiken/builtin.{length_of_bytearray}
+
+pub fn is_empty(bytes: ByteArray) -> Bool {
+  length_of_bytearray(bytes) == 0
+}
+
+test is_empty_1() {
+  is_empty(#[]) == True
+}