Add `--force` requirement to `del --recursive`

Following s3cmd, s4cmd should consider requiring a `--force` flag for `del --recursive` calls. Because this is currently not required, unintended data loss could occur. I can submit a PR if this is in line with the project maintainer.

The issue names no file or test. Start at the command-line entry point and trace handling for `del --recursive`; determine how the existing options are parsed and how similar safety checks work. Done means recursive deletion requires `--force`, with coverage for both accepted and rejected command invocations.

Written by the indexing model from the issue text.