Move branding and package install into cargo-run (#4266)

* Move branding asset fetch into cargo-run

* Move frontend npm install into cargo-run

* Rename branding::ensure to branding::setup

* Wording nits

---------

Co-authored-by: Keavon Chambers <keavon@keavon.com>

tools/cargo-run/src/branding.rs

@@ -0,0 +1,40 @@
+use crate::cmd::prelude::*;
+use crate::{Error, workspace_dir};
+
+const INFO_FILE: &str = ".branding";
+const DIR: &str = "branding";
+
+pub fn setup() -> Result<(), Error> {
+	let workspace = workspace_dir();
+	let info_path = workspace.join(INFO_FILE);
+	let dir_path = workspace.join(DIR);
+	let marker_path = dir_path.join(INFO_FILE);
+
+	let info = std::fs::read_to_string(&info_path).map_err(|e| Error::Io(e, format!("reading '{}'", info_path.display())))?;
+
+	if let Ok(marker) = std::fs::read_to_string(&marker_path)
+		&& marker == info
+	{
+		return Ok(());
+	}
+
+	let mut lines = info.lines().map(str::trim).filter(|l| !l.is_empty());
+	let url = lines
+		.next()
+		.ok_or_else(|| Error::Io(std::io::Error::other("missing URL"), format!("parsing '{}'", info_path.display())))?;
+	let sha256 = lines
+		.next()
+		.ok_or_else(|| Error::Io(std::io::Error::other("missing SHA-256"), format!("parsing '{}'", info_path.display())))?;
+
+	eprintln!("Downloading branding assets from <{url}>...");
+
+	if dir_path.exists() {
+		std::fs::remove_dir_all(&dir_path).map_err(|e| Error::Io(e, format!("removing '{}'", dir_path.display())))?;
+	}
+
+	utils::internal("download").args([url, sha256, DIR, "--extract", "--strip", "1"]).dir(&workspace).run()?;
+
+	std::fs::copy(&info_path, &marker_path).map_err(|e| Error::Io(e, format!("writing '{}'", marker_path.display())))?;
+
+	Ok(())
+}