Allow overriding default implementation of TemporaryDirectory

[jonerickson]

This PR arises out of the need to change the default implementation of the TemporaryDirectory service. In our story, serving a multi-tenant application and using this package to backup each individual tenant's DB, we needed the ability to customize the temporary directory's location. Because we have a large number of tenants, we elected to create a batch job to backup each tenant's DB. Because of this, we are running into the issue where multiple jobs are trying to use the same temporary directory. As you can imagine, this creates chaos. We now have the ability to set the file path based on the tenant allowing each tenant to use their own temporary directory.

Because the package relies on Spatie's temporary directory package, we needed to create an adapter to extend the new TemporaryDirectory interface. This adapter just simply creates a new instance of TemporaryDirectory and then passes all calls to the default implementation.

With this PR, we can now do the following. This allows use to set the location in our own implementation's constructor.

$this->app->extend(TemporaryDirectory::class, function () {
    return new TenantTemporaryDirectory();
});

I chose not to include all the methods in the contract from the spatie/temporary-directory package as this would create a cross-package dependency that I think would not be the best choice.