Allow ACL to be set by the package job input payload.

[matvp91]

Is your feature request related to a problem? Please describe.
In f4d5a2d we removed support for "per object ACL" due to Backblaze B2 having the concept of a "bucket ACL". Ideally, people put a CDN in front of their bucket.

However, there are providers that come with a built-in CDN such as DigitalOcean thus having some sort of ACL set to "public-read" should be there.

Describe the solution you'd like
When a package job is set, we can introduce a public key that sets the ACL to public-read, it's up to the user to define it properly if they work with an S3 provider with a preconfigured CDN.

When public is undefined, we don't set ACL. When it's false, we set private and when it's true, we set public-read.