Roast is ready for the most part

[uncomfyhalomacro]

• where .cargo/config.toml should be located obs-service-cargo#96
• Plan to reuse some logic in obs-service-cargo
• https://github.com/openSUSE-Rust/roast
• Fully implement cargo vendor home registry

[uncomfyhalomacro]

Closed with fab49c8

What was resolved?

• We don't have to worry about config.toml. We can even just respect what was shipped as well from the source since we won't need to regenerate it.
• We didn't even use obs-service-cargo. We just used roast and rustsec.