Fatal error in migrate_plus_module_implements_alter() when $hook parameter receives integer instead of string in Drupal 11.x

Problem/Motivation

With Drupal 11.x, the migrate_plus module throws a TypeError when enabling modules:
TypeError: migrate_plus_module_implements_alter(): Argument #2 ($hook) must be of type string, int given, called in /core/lib/Drupal/Core/Hook/HookCollectorPass.php on line 239 in migrate_plus_module_implements_alter() (line 99 of /modules/contrib/migrate_plus/migrate_plus.module).

This is caused by core issue #3508292 where update hooks are incorrectly being registered as normal hooks, causing the HookCollectorPass to pass integers (from update hook numbers) instead of strings to hook_module_implements_alter() implementations.

Steps to reproduce

1. Install Drupal 11.x
2. Install migrate_plus module
3. Try to install additional modules or clear cache
4. Observe the TypeError

Environment

- Drupal core: 11.2.4
- Migrate Plus: 6.0.8
- PHP: 8.3.25

Proposed resolution

Add type checking in migrate_plus_module_implements_alter() to handle cases where $hook is an integer. Since migrate_plus only processes specific string hook names, return early when $hook is not a string.

Remaining tasks

User interface changes

API changes

Data model changes