Add validation of extra names (#257)

Extends #254 

Adds validation of extra names provided by users in `pip-compile` e.g. 

```
error: invalid value 'foo!' for '--extra <EXTRA>': Extra names must start and end with a
letter or digit and may only contain -, _, ., and alphanumeric characters
```

We'll want to add something similar to `PackageName`. I'd be curious to
improve the AP, making the unvalidated nature of `::normalize` clear?
Perhaps worth pursuing later though as I don't have a better idea.

crates/puffin-cli/tests/pip_compile.rs

@@ -444,6 +444,59 @@ optional-dependencies.foo = [
     Ok(())
 }
 
+/// Request an extra with a name that does not conform to the specification.
+#[test]
+fn invalid_extra_name() -> Result<()> {
+    let temp_dir = assert_fs::TempDir::new()?;
+    let cache_dir = assert_fs::TempDir::new()?;
+    let venv = temp_dir.child(".venv");
+
+    Command::new(get_cargo_bin(BIN_NAME))
+        .arg("venv")
+        .arg(venv.as_os_str())
+        .arg("--cache-dir")
+        .arg(cache_dir.path())
+        .current_dir(&temp_dir)
+        .assert()
+        .success();
+    venv.assert(predicates::path::is_dir());
+
+    let pyproject_toml = temp_dir.child("pyproject.toml");
+    pyproject_toml.touch()?;
+    pyproject_toml.write_str(
+        r#"[build-system]
+requires = ["setuptools", "wheel"]
+
+[project]
+name = "project"
+dependencies = []
+optional-dependencies.foo = [
+    "django==5.0b1",
+]
+"#,
+    )?;
+
+    insta::with_settings!({
+        filters => vec![
+            (r"\d+(ms|s)", "[TIME]"),
+            (r"#    .* pip-compile", "#    [BIN_PATH] pip-compile"),
+            (r"--cache-dir .*", "--cache-dir [CACHE_DIR]"),
+        ]
+    }, {
+        assert_cmd_snapshot!(Command::new(get_cargo_bin(BIN_NAME))
+            .arg("pip-compile")
+            .arg("pyproject.toml")
+            .arg("--extra")
+            .arg("invalid name!")
+            .arg("--cache-dir")
+            .arg(cache_dir.path())
+            .env("VIRTUAL_ENV", venv.as_os_str())
+            .current_dir(&temp_dir));
+    });
+
+    Ok(())
+}
+
 /// Resolve a specific Flask wheel via a URL dependency.
 #[test]
 fn compile_wheel_url_dependency() -> Result<()> {