Allow configuring output .box file name

#### Description

`vagrant package` has a `--output NAME` option that allows setting the name of the output .box file.

Currently the Vagrant plugin for Packer [hard-codes this to `package.box`][1]

#### Use Case(s)

This will simplify the amount of out-of-packer processing required, when using the vagrant builder.

#### Potential configuration

```
{
"output_name": "my-name-{{ user `version` }}.box"
}
```

#### Potential References

[the current implementation][1]

[1]: https://github.com/hashicorp/packer-plugin-vagrant/blob/main/builder/vagrant/driver_2_2.go#L83