Add test to demonstrate issue python#9655

This test currently fails with this error:

    AssertionError: Command 3 (dmypy check -- bar.py) did not give expected output
    --- Captured stderr call ---
    Expected:
      bar.py:2: error: Unused "type: ignore" comment (diff)
      == Return code: 1                              (diff)
    Actual:
      (empty)

It demonstrates a bug that when an module is removed using
`FineGrainedBuildManager.update` because it is not "seen" by
`fine_grained_increment_follow_imports`, then "unused type: ignore"
warnings disappear from subsequent checks.

Ref: python#9655

Author: meshy

test-data/unit/daemon.test

@@ -615,3 +615,20 @@ b: str
 from demo.test import a
 [file demo/test.py]
 a: int
+
+[case testUnusedTypeIgnorePreservedOnRerun]
+-- Regression test for https://github.com/python/mypy/issues/9655
+$ dmypy start -- --warn-unused-ignores --no-error-summary --hide-error-codes
+Daemon started
+$ dmypy check -- bar.py
+bar.py:2: error: Unused "type: ignore" comment
+== Return code: 1
+$ dmypy check -- bar.py
+bar.py:2: error: Unused "type: ignore" comment
+== Return code: 1
+
+[file foo/__init__.py]
+[file foo/empty.py]
+[file bar.py]
+from foo.empty import *
+a = 1  # type: ignore