Add tests that verify the `rad` binary does not panic when its stdout
is a broken pipe (e.g., `rad config | head -1`).
Rust (since 1.62) ignores SIGPIPE by default (see [Rust #62569]),
causing `println!` to panic with "failed printing to stdout: Broken
pipe" instead of exiting silently. This is the standard Unix behaviour
expected of CLI tools.
These tests currently fail on `rad config` and `rad self`, and are set to `ignore`, to be enabled when fixed.
[Rust #62569]: https://github.com/rust-lang/rust/issues/62569
8f4b90db7b