feat: add dlp: false passthrough option for egress routes

Routes with `dlp: false` skip all DLP scanning (including CRLF injection,
which cannot be disabled via `dlp.outbound_detectors: false`) and tunnel
HTTPS connections without TLS interception so the client sees the server's
real certificate. Fixes Docker image pulls, which fail when the proxy MITM's
the TLS handshake and the container doesn't trust the per-bottle CA.

Closes #462

tests/unit/test_manifest_egress.py

@@ -337,6 +337,19 @@ class TestDlp(unittest.TestCase):
                 "bogus": True,
             }}])
 
+    def test_dlp_false_sets_passthrough(self):
+        b = _bottle([{"host": "x.example", "dlp": False}])
+        r = b.egress.routes[0]
+        self.assertTrue(r.DlpPassthrough)
+
+    def test_dlp_passthrough_default_false(self):
+        b = _bottle([{"host": "x.example"}])
+        self.assertFalse(b.egress.routes[0].DlpPassthrough)
+
+    def test_dlp_not_dict_or_false_rejected(self):
+        with self.assertRaises(ManifestError):
+            _bottle([{"host": "x.example", "dlp": "nope"}])
+
     def test_outbound_on_match_omitted_is_empty(self):
         b = _bottle([{"host": "x.example"}])
         self.assertEqual("", b.egress.routes[0].OutboundOnMatch)