Add uv tool dir --bin to show executable directory (#5160)

## Summary

Closes https://github.com/astral-sh/uv/issues/5159.

crates/uv-cli/src/lib.rs

@@ -2067,7 +2067,7 @@ pub enum ToolCommand {
     #[command(alias = "ensurepath")]
     UpdateShell,
     /// Show the tools directory.
-    Dir,
+    Dir(ToolDirArgs),
 }
 
 #[derive(Args)]
@@ -2168,6 +2168,17 @@ pub struct ToolInstallArgs {
 #[allow(clippy::struct_excessive_bools)]
 pub struct ToolListArgs;
 
+#[derive(Args)]
+#[allow(clippy::struct_excessive_bools)]
+pub struct ToolDirArgs {
+    /// Show the directory into which `uv tool` will install executables.
+    ///
+    /// By default, `uv tool dir` shows the directory into which the tool Python environments
+    /// themselves are installed, rather than the directory containing the linked executables.
+    #[arg(long, alias = "executable")]
+    pub bin: bool,
+}
+
 #[derive(Args)]
 #[allow(clippy::struct_excessive_bools)]
 pub struct ToolUninstallArgs {