Allow uncommitted changes during clippy fix xtask (#8396)

Add flag to allow uncommitted changes when running clippy fix xtask

Author: jmpesp

dev-tools/xtask/src/clippy.rs

@@ -14,6 +14,9 @@ pub struct ClippyArgs {
     /// Automatically apply lint suggestions.
     #[clap(long)]
     fix: bool,
+    /// Allow uncommitted changes
+    #[clap(long)]
+    allow_dirty: bool,
     /// Error format passed to `cargo clippy`.
     #[clap(long, value_name = "FMT")]
     message_format: Option<String>,
@@ -27,6 +30,10 @@ pub fn run_cmd(args: ClippyArgs) -> Result<()> {
         command.arg("--fix");
     }
 
+    if args.allow_dirty {
+        command.arg("--allow-dirty");
+    }
+
     // Pass along the `--message-format` flag if it was provided.
     //
     // We don't really care about validating that it's a valid argument to