xtask: Add command for checking packages conform to certain standards (#15236)

This PR adds a new `xtask` command for checking that packages conform to
certain standards.

Still a work-in-progress, but right now it checks:

- If `[lints] workspace = true` is set
- If packages are using non-workspace dependencies

Release Notes:

- N/A

tooling/xtask/src/main.rs

@@ -16,6 +16,8 @@ enum CliCommand {
     /// Runs `cargo clippy`.
     Clippy(tasks::clippy::ClippyArgs),
     Licenses(tasks::licenses::LicensesArgs),
+    /// Checks that packages conform to a set of standards.
+    PackageConformity(tasks::package_conformity::PackageConformityArgs),
 }
 
 fn main() -> Result<()> {
@@ -24,5 +26,8 @@ fn main() -> Result<()> {
     match args.command {
         CliCommand::Clippy(args) => tasks::clippy::run_clippy(args),
         CliCommand::Licenses(args) => tasks::licenses::run_licenses(args),
+        CliCommand::PackageConformity(args) => {
+            tasks::package_conformity::run_package_conformity(args)
+        }
     }
 }