Minimal publishing assistant (#512)

Minimal publishing assistant (#512)

* Suppress warnings on unused package at top level

* First complete minimal publishing workflow

Only for repositories, many checks still missing, like: whitelist, version
conflict, buildability...

* Also working with source archives

* Deprecate --hash, --commit

Instead, the commit is simply a second optional argument

* Give upload URL for the PR and place manifest in ...

...alire/releases

* Check if in workspace for proper file placement

and also discourage publishing a crate within an unrelated workspace.

* Disable --hash test

* Tests for publishing and fixes for detected errors

To test without resorting to actual remote sources, we use --force which allows
local (file:) URLs.

* Workaround for Windows temporary failed deletion

Something about a git repository makes Ada.Directories.Delete_Tree to fail (my
guess that this is git related).