Add missing `rust_toolchain` configuration flags to `rust.toolchain` tag class

Hi,

I'm very new to the field, so please let me know if the information I communicate here is useful enough for debugging.

I have the following dependency in `MODULE.bazel`
```starlark
bazel_dep(name = "rules_rust", version = "0.41.1")
rust = use_extension("@rules_rust//rust:extensions.bzl", "rust")
rust.toolchain(
edition = "2024",
versions = ["1.77.2"],
)
use_repo(rust, "rust_toolchains")
register_toolchains("@rust_toolchains//:all")
```

When running a simple `blaze test` command, I get the following error (I've omitted the more verbose parts):
```
ERROR: .../external/rules_rust~/util/process_wrapper/BUILD.bazel:31:36: Compiling Rust (without process_wrapper) bin process_wrapper (6 files) [for tool] failed: (Exit 1): sandbox-exec failed: error executing Rustc command
...
error: linking with `external/zig_sdk/tools/aarch64-macos-none/c++` failed: exit status: 1
|
= note: env -u ...
= note: error: unable to find dynamic system library 'resolv' using strategy 'paths_first'. searched paths: ...
```

Does anybody know what's happening here, and how to fix this please?

The report uses MODULE.bazel and @rules_rust//rust:extensions.bzl, with the failure observed while building util/process_wrapper/BUILD.bazel. Read the rust.toolchain tag definition and reproduce the reported blaze test command, then determine which rust_toolchain flags are missing from the interface. Done means the required flags are supported and the configuration is covered by relevant tests.

Written by the indexing model from the issue text.