Bring modular arc_summary from TrueNAS
Fix an ARC attribute
Load apps dynamically
Remove deprecated url entries
Add minimalistic hook framework

Each app register itself in the appPool instance, using an AppHook class
containing the appropriate hook methods.
Use base_js hook in the base template for extra js files
Fix html script tags
Allow an URL attribute in main nav module
Detach reporting from system app
Add a hook for the top menu items
Use for index counter in case of conflicting names
Add hooks for the reporting module

This completes the separation of reporting from the system app.
Remove forgotten debug line
Add hook infrastructure for form on done method
Call parent done method in sharing forms
Add comment of form done hook prototype in base hook class
Add a new hook on form delete
Unduplicate the code to get a list from the hooks
Add a hook to add extra items to the system info view

The hook is called system_info and returns a list of dict, with name and
value.
While I'm here document other hooks.
Bring pre_build_options tree method from TrueNAS