tests: Add a test for AVM1 in AVM2

tests/tests/swfs/avm2/mixed_avm/input.json

@@ -0,0 +1,17 @@
+[
+    {
+        "type": "Wait"
+    },
+    {
+        "type": "Wait"
+    },
+    {
+        "type": "MouseMove",
+        "pos": [10.0, 10.0]
+    },
+    {
+        "type": "MouseDown",
+        "pos": [10.0, 10.0],
+        "btn": "Left"
+    }
+]

tests/tests/swfs/avm2/mixed_avm/output.txt

@@ -0,0 +1,6 @@
+Starting load...
+hello from avm1!
+[object AVM1Movie]
+[object ApplicationDomain]
+Load complete!
+onmousedown at 10, 10!

tests/tests/swfs/avm2/mixed_avm/test.toml

@@ -0,0 +1,3 @@
+# NOTE: In FP, the "hello from avm1!" log appears after "Load complete",
+# but this is likely due to Ruffle's incorrect chunked loading behaviors.
+num_ticks = 3