Support "republish" in Cloudsmith upload

### Checklist - [x] I added a descriptive title - [x] I searched open requests and couldn't find a duplicate ### What is the idea? Cloudsmith has a republish flag which allows overwriting existing packages: ``` ❯ cloudsmith upload conda --help | rg -A3 republish --republish / --no-republish If true, the uploaded package will overwrite any others with the same attributes (e.g. same version); otherwise, it will be flagged as a duplicate. ``` It would be great to support this here also. ### Why is this needed? Otherwise you get an error in the UI and have to manually cleanup packages. ### What should happen? The `create_package` function calls the `upload/conda` endpoint: https://github.com/conda/rattler/blob/46eadfe9b6f1da676ea537d0e196858b2ab4457c/crates/rattler_upload/src/upload/cloudsmith.rs#L298-L304 Passing only the `package_file` as the POST data: https://github.com/conda/rattler/blob/46eadfe9b6f1da676ea537d0e196858b2ab4457c/crates/rattler_upload/src/upload/cloudsmith.rs#L308-L315 The endpoint supports a `republish: boolean` argument: <img width="1040" height="871" alt="Image" src="https://github.com/user-attachments/assets/799331da-c070-4f1e-8af5-25950b8ec895" /> https://docs.cloudsmith.com/api/packages/upload/conda <br> This should be exposed in the function arguments (and calling functions) so that clients such as `pixi publish` can allow overwriting existing packages ### Additional Context _No response_