Bug with 'influxdb3 show databases' when outputting to parquet

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The `influxdb3 show databases` command lists `parquet` as a supported output format but doesn't provide a `-o`,`--output` option to specify a file to write output to. You can't output raw Parquet in a command line.

__Steps to reproduce:__

1. Create one or more databases in an InfluxDB 3 Core or Enterprise instance.
2. Run the following command to list databases and format the output as Parquet:

```sh
influxdb3 show databases --format parquet
```

__Expected behaviour:__

I would expect the show commands, if they are to support Parquet output, would also include a `-o`, `--output` option to output the raw Parquet to a file (like the `influxdb3 query` command does).

__Actual behaviour:__

When you try to output Parquet on the command line, you get an error similar to:

```
Show command failed: invalid utf-8 sequence of 1 bytes from index 19
```

Start with the `influxdb3 show databases` command and compare its format and output options with the `influxdb3 query` command. Verify the Parquet path does not treat raw output as UTF-8; done means `--format parquet` can write valid raw Parquet to a file through `-o` or `--output`.

Written by the indexing model from the issue text.