Simplify managing crates.io ownership

[bendk]

Right now it's hard to manage our crates.io ownership, since we publish several different crates. What if we wrote a script to simplify it?

The script would contain the correct list of owners. For each published uniffi crate it would check the current list of owners and add/remove owners to match the correct list. cargo owner provides all the low-level functionality we would need. For safety, it should display the proposed list of changes and require the user to type yes before actually doing any work.

┆Issue is synchronized with this Jira Task ┆Issue Number: UNIFFI-161

[jplatte]

Adding a GitHub team as an owner also works by entering github:<orgname>:<groupname>.

edit: though last time this topic was mentioned on Matrix, @badboy noted

last time I checked we couldn't use groups inside the mozilla organisation. with the saml integration done now we could approach the github admins and see if that becomes possible