Currently, the idna_adapter crate is hosted under the "github.com/hsivonen" prefix.
Given that idna_adapter's sole publicly reported dependant is the idna crate, I propose moving idna_adapter source code to the servo/rust-url repository.

- Centralization: Simplifies management and maintenance by centralizing related codebases.
- Consistency: Ensures consistent development and versioning of interdependent crates.
- Security: Enhances security by consolidating code under the main
servo organization, reducing the risk of fragmentation.
- Transparency: Improves transparency and trust by having all related code in the main
servo repository.