Add xtask for finding crates with missing licenses (#11776)

This PR adds a new `cargo xtask licenses` command for finding crates
with missing license files.

A number of crates were uncovered that were missing a license file, and
have had the appropriate license file added.

Release Notes:

- N/A

tooling/xtask/src/main.rs

@@ -1,6 +1,7 @@
-use std::process::Command;
+mod tasks;
+mod workspace;
 
-use anyhow::{bail, Context, Result};
+use anyhow::Result;
 use clap::{Parser, Subcommand};
 
 #[derive(Parser)]
@@ -13,72 +14,15 @@ struct Args {
 #[derive(Subcommand)]
 enum CliCommand {
     /// Runs `cargo clippy`.
-    Clippy(ClippyArgs),
+    Clippy(tasks::clippy::ClippyArgs),
+    Licenses(tasks::licenses::LicensesArgs),
 }
 
 fn main() -> Result<()> {
     let args = Args::parse();
 
     match args.command {
-        CliCommand::Clippy(args) => run_clippy(args),
+        CliCommand::Clippy(args) => tasks::clippy::run_clippy(args),
+        CliCommand::Licenses(args) => tasks::licenses::run_licenses(args),
     }
 }
-
-#[derive(Parser)]
-struct ClippyArgs {
-    /// Automatically apply lint suggestions (`clippy --fix`).
-    #[arg(long)]
-    fix: bool,
-
-    /// The package to run Clippy against (`cargo -p <PACKAGE> clippy`).
-    #[arg(long, short)]
-    package: Option<String>,
-}
-
-fn run_clippy(args: ClippyArgs) -> Result<()> {
-    let cargo = std::env::var("CARGO").unwrap_or_else(|_| "cargo".to_string());
-
-    let mut clippy_command = Command::new(&cargo);
-    clippy_command.arg("clippy");
-
-    if let Some(package) = args.package.as_ref() {
-        clippy_command.args(["--package", package]);
-    } else {
-        clippy_command.arg("--workspace");
-    }
-
-    clippy_command
-        .arg("--release")
-        .arg("--all-targets")
-        .arg("--all-features");
-
-    if args.fix {
-        clippy_command.arg("--fix");
-    }
-
-    clippy_command.arg("--");
-
-    // Deny all warnings.
-    clippy_command.args(["--deny", "warnings"]);
-
-    eprintln!(
-        "running: {cargo} {}",
-        clippy_command
-            .get_args()
-            .map(|arg| arg.to_str().unwrap())
-            .collect::<Vec<_>>()
-            .join(" ")
-    );
-
-    let exit_status = clippy_command
-        .spawn()
-        .context("failed to spawn child process")?
-        .wait()
-        .context("failed to wait for child process")?;
-
-    if !exit_status.success() {
-        bail!("clippy failed: {}", exit_status);
-    }
-
-    Ok(())
-}