[1.0.x] Simple Body Class

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I looked at 1.0.x at commit 72d0c82.

1. src/Hook/HelpHooks.php, line 24. The match has a single arm and no default, so any route name other than help.page.simple_body_class throws UnhandledMatchError. hook_help() is invoked for other routes: core's own HelpEmptyPageTest calls it with the front page route name. Return an empty string for anything the module does not describe.

2. src/Hook/HelpHooks.php, line 25. The help text is a literal English string containing markup. Interface text has to be translatable, and help is normally a render array rather than a concatenated string.

3. src/Hook/ThemeHooks.php, lines 33 and 37. Both values are appended without checking them, so a node or content type with no classes adds an empty string to $variables['attributes']['class']. Skip empty values.

4. src/Hook/HelpHooks.php, line 10. The docblock asterisks are not indented, unlike the other two hook classes.

5. src/Hook/FormHooks.php line 16, src/Hook/HelpHooks.php line 11, src/Hook/ThemeHooks.php line 12. Drupal does not have form hooks, help hooks and theme hooks as categories. The usual description is "Hook implementations for the [module name] module", where [module name] is the name given in the .info.yml file.

Coding standards are clean: phpcs with the Drupal and DrupalPractice standards reports nothing on the PHP files.

Hook implementations for the [module name] module. can be used when all the hooks are in a .module file. With three different classes that implement OOP hooks, a different description for each class, like Help-related hooks for the Simple Body Class module. or Theme-related hooks for the Simple Body Class module. is better, IMO.