fix: Update state of message when fully downloading it

If a message partially downloaded before is already IMAP-seen upon a full download, it should be
updated to `InSeen`. OTOH if it's not IMAP-seen, but already `InNoticed` locally, its state should
be preserved. So we take the maximum of two states.

src/receive_imf.rs

@@ -1575,7 +1575,7 @@ INSERT INTO msgs
 ON CONFLICT (id) DO UPDATE
 SET rfc724_mid=excluded.rfc724_mid, chat_id=excluded.chat_id,
     from_id=excluded.from_id, to_id=excluded.to_id, timestamp_sent=excluded.timestamp_sent,
-    type=excluded.type, msgrmsg=excluded.msgrmsg,
+    type=excluded.type, state=max(state,excluded.state), msgrmsg=excluded.msgrmsg,
     txt=excluded.txt, txt_normalized=excluded.txt_normalized, subject=excluded.subject,
     txt_raw=excluded.txt_raw, param=excluded.param,
     hidden=excluded.hidden,bytes=excluded.bytes, mime_headers=excluded.mime_headers,