feat: add reencrypt command

tests/commands/test_reencrypt.py

@@ -0,0 +1,16 @@
+import pytest
+
+from halig.commands.reencrypt import ReencryptCommand
+
+
+@pytest.fixture()
+def reencrypt_command(settings):
+    return ReencryptCommand(settings)
+
+
+@pytest.mark.usefixtures('notes')
+def test_reencrypt(reencrypt_command):
+    reencrypt_command.run()
+    for note_path in reencrypt_command.traverse():
+        with note_path.open("rb") as f:
+            assert reencrypt_command.encryptor.decrypt(f.read()) == b""