Inline PublicUploadsController before_action
Inline PublicUploadsController before_action

The implementation in `show` never gets called because the
`redirect_to_asset_host` `before_action` unconditionally
redirects. I'm inlining the implementation to make it clear that the
rest of the methods in this class can be removed.

alphagov/whitehall,alphagov/whitehall,alphagov/whitehall,alphagov/whitehall