Allow parse-time evaluation of calls, pipelines and subexpressions (#9499)

Co-authored-by: Antoine Stevan <44101798+amtoine@users.noreply.github.com>

crates/nu-command/tests/commands/path/dirname.rs

@@ -135,3 +135,9 @@ fn replaces_dirname_of_way_too_many_levels() {
     let expected = join_path_sep(&["eggs", "some/dir/with/spam.txt"]);
     assert_eq!(actual.out, expected);
 }
+
+#[test]
+fn const_path_dirname() {
+    let actual = nu!("const name = ('spam/eggs.txt' | path dirname); $name");
+    assert_eq!(actual.out, "spam");
+}