[Minor nit] toolchain install missing download detials

[nuke-web3]

Attempting to install the toolchain on a very slow (KB/s) hangs on Extracting... but I believe that message is printed too early, while the download is progressing still:

cargo-wasix/src/toolchain.rs

Lines 602 to 612 in 07d5637

	// Download and extract sysroot.
	eprintln!(
	"Downloading sysroot from url '{}'...",
	&sysroot_asset.browser_download_url
	);
	let res = client
	.get(&sysroot_asset.browser_download_url)
	.send()?
	.error_for_status()?;
	eprintln!("Extracting...");

Some minimal progress bar would be great, but at least ensuring that it is clear what is blocking the install step-wise would be a very nice fix to have.

---

# Run in a rust crate:
cargo wasix build

Finding latest release... (https://api.github.com/repos/wasix-org/rust/releases/latest)...
Toolchain path ~/.local/share/cargo-wasix/toolchains/x86_64-unknown-linux-gnu_v2023-11-01.1 already exists - deleting existing files!
Downloading sysroot from url 'https://github.com/wasix-org/rust/releases/download/v2023-11-01.1/wasix-libc.tar.gz'...
Extracting...
Downloading Rust toolchain from url 'https://github.com/wasix-org/rust/releases/download/v2023-11-01.1/rust-toolchain-x86_64-unknown-linux-gnu.tar.gz'...
Extracting...

# hangs for ~1 minute or more here

Downloaded toolchain x86_64-unknown-linux-gnu to /home/nuke/.local/share/cargo-wasix/toolchains/x86_64-unknown-linux-gnu_v2023-11-01.1/rust
Activating rustup toolchain wasix at /home/nuke/.local/share/cargo-wasix/toolchains/x86_64-unknown-linux-gnu_v2023-11-01.1/rust...
Running rustup toolchain link wasix /home/nuke/.local/share/cargo-wasix/toolchains/x86_64-unknown-linux-gnu_v2023-11-01.1/rust:
rustup toolchain wasix was linked and is now available!

[theduke]

Yes agreed, the current output isn't great.