[DX] Implement hook_hook_info() to help organize module code

Describe your issue or idea

This is a follow-up from https://github.com/backdrop/backdrop-issues/issues/2954 where we are discussing how to better organize our code.

modules must implement hook_hook_info() to allow using a separate file, like Token, Path and Redirect does.

These are the tools I recommend we use hook_hook_info() on

• [ ] Block (class) => includes/modulename.block.class.inc
• [ ] Comment - hook_comment_*() => modulename.comment.inc
• [ ] Files - hook_file_*() => modulename.file.inc
• [ ] Menu - hook_menu_*() => modulename.menu.inc
• [ ] Menu - hook_menu_link_*() => modulename.menu_link.inc
• [ ] Node - hook_node_*() => modulename.node.inc
• [ ] Taxonomy - hook_taxonomy_term_*() => modulename.taxonomy_term.inc
• [ ] Taxonomy - hook_taxonomy_vocabulary_*() => modulename.taxonomy_vocabulary.inc
• [ ] User - hook_user_*() => modulename.user.inc