bpo-42882: Add test_embed.test_unicode_id_init() (GH-24198)

Test that _PyUnicode_FromId() works when Python is initialized
multiples times.
diff --git a/Lib/test/test_embed.py b/Lib/test/test_embed.py
index a7d9121..6833b25 100644
--- a/Lib/test/test_embed.py
+++ b/Lib/test/test_embed.py
@@ -1472,5 +1472,11 @@ def test_audit_run_stdin(self):
                                       timeout=support.SHORT_TIMEOUT,
                                       returncode=1)
 
+class MiscTests(EmbeddingTestsMixin, unittest.TestCase):
+    def test_unicode_id_init(self):
+        # bpo-42882: Test that _PyUnicode_FromId() works
+        # when Python is initialized multiples times.
+        self.run_embedded_interpreter("test_unicode_id_init")
+
 if __name__ == "__main__":
     unittest.main()