Make cargo owners consistent and ensure it stays so

[rsheeter]

fontations, fontc, and sleipnir crates appear to have inconsistent owners. To fix:

• Setup a GH team and make it owner of all our crates
  • https://doc.rust-lang.org/cargo/reference/publishing.html#cargo-owner
• Setup CI to check the team is assigned as owner for all crates
  • I believe https://doc.rust-lang.org/cargo/commands/cargo-owner.html can be used to list for this purpose