Add new plugin hooks documentation

[cconard96]

WIP adding documentation from glpi-project/glpi#19450 to enhance the plugin hook documenation. This is all to add the documentation for the missing hooks, improve the overall quality of the documentation, document the new Hooks and HookManager classes, and make it less likely that the hook documentation becomes out of date again.

[cedric-anne]

The hook names should probably be clarified. Developers may try to use the documented name as a string.
Maybe the FQCN should be added, like this: \Glpi\Plugins\Hooks::ADD_CSS_ANONYMOUS_PAGE.

[trasher]

Diff is too huge, branch must be rebased

[cconard96]

Rebased. The documentation here, apart from the description at the very top, was automatically generated by the tools:generate_hooks_documentation CLI command in GLPI core. Any issues with the actual hooks documentation need fixed in the command or in the PHPDoc of the Hooks constants which are the source of this info.