feat: Remove original file stem from filenames in the blobstorage (#4309)

This way filenames in the blobstorage are just random hex numbers. This also allows us to get rid of
the `sanitize-filename` dependency.

This also requires `Param::Filename` to be set to "debug_logging*.xdc" for messages containing
logging webxdc-s, otherwise they are not detected properly. This is done in "fix:
Message::set_file_from_bytes(): Set Param::Filename", so don't forget to update senders as well.

python/tests/test_2_increation.py

@@ -50,7 +50,6 @@ class TestOnlineInCreation:
         src = tmp_path / "file.txt"
         src.write_text("hello there\n")
         msg = chat.send_file(str(src))
-        assert msg.filename.startswith(os.path.join(ac1.get_blobdir(), "file"))
         assert msg.filename.endswith(".txt")
 
     def test_forward_increation(self, acfactory, data, lp):