Add split-debuginfo print option
This option prints all supported values for `-Csplit-debuginfo=..`, i.e. only stable ones on stable/beta and all of them on nightly/dev.
Motivated by 1.65.0 regression causing builds with the following entry in `Cargo.toml` to fail on Windows:
```toml
[profile.dev]
split-debuginfo = "unpacked"
```
See https://github.com/rust-lang/cargo/pull/11347 for details.
This will lead to closing https://github.com/rust-lang/rust/issues/103976.
Guillaume Gomez
92f1c6f884