fix(parser): namespace pollution of constants by use module.nu (#15518)

A bug introduced by #14920 

When `use module.nu` is called, all exported constants defined in it are
added to the scope.

# Description

On the branch of empty arguments, the constant var_id vector should be
empty, only constant_values (for `$module.foo` access) are injected.

# User-Facing Changes

# Tests + Formatting

~todo!~

adjusted

# After Submitting

tests/repl/test_modules.rs

@@ -143,6 +143,10 @@ fn export_module_which_defined_const() -> TestResult {
     run_test(
         r#"module spam { export const b = 3; export const c = 4 }; use spam; $spam.b + $spam.c"#,
         "7",
+    )?;
+    fail_test(
+        r#"module spam { export const b = 3; export const c = 4 }; use spam; $b"#,
+        "variable not found",
     )
 }