Allow uploading files that would be removed once downloaded

via @pascal-pfeiffer

#### Is your feature request related to a problem? Please describe

Some apps may provide a user-scoped file downloads which can be freed up once downloaded.

#### Describe the solution you'd like

Enhance the existing `site.upload` function with a new param that would indicate deletion after the first download.

#### Describe alternatives you've considered

(A clear and concise description of any alternative solutions or features you've considered.)

#### Additional context

Add any other context or screenshots about the feature request here.