Progressbar writer

[anysomewhere]

Use the writer from the logger to write the progressbar output to. The logger is available in every function that uses a progressbar but it is often un(der)used. As the default output writer for loggers is os.Stderr as which is the default for the progressbar as well, this won't change anything for default logger users, but it enables users of the library to redirect the progressbar output.

[bdon]

Thanks, agreed this would be useful and has a lot of overlap with https://github.com/protomaps/go-pmtiles/issues/117 so maybe we should move to slog soon which should encompass hiding progress. What specific subcommand do you need this for?

[anysomewhere]

Is there a requirement to move to slog? That would make progressbars more or less impossible.