[Feature] Ability to manually update mod if the `.pwr` file is downloaded.

In the event a user fails to connect to the server, the user should be able to manually update their game if they have the correct `.pwr` update file.

Suggested usage:
```
./beans-rs update --from of-20to21.pwr
```

Start at the `beans-rs update --from of-20to21.pwr` command entry point and trace how updates currently obtain their files. Support applying a locally supplied `.pwr` file when the server cannot be reached, and verify that the game updates successfully from the downloaded file.

Written by the indexing model from the issue text.