Check if an element (module / extra) should be part of a group, based on its name, given groups conditions.

An element be in multiple groups if it matches inclusion conditions.

Also generate the display name && css classes.

If no group is specified, we default to the empty group (first to be displayed) rather than hidding the element.

Generate the group container needed in sidebar_items.

This maintain the group order defined in the initial config.

Transform the group matcher input format to allow Callables & Regexps.

The following is valid input:

groups_for_modules: {
  # List of regexps
  'My group' => [
    # Regexp
    %r{^ClassA$},
    # Callable
    ->(name) { name.start_with?('ModuleB'),
    # Hash with the following keys:
    {
      # Inclusion needs to be either a Regexp or a Callable
      inclusion:   %r{^ModuleB.*},
      # A callable that returns an array of css classes
      css_classes: ->(name) do
        ['text-left', name.start_with?('Module') ? 'module' : 'class'],
      end,
      # A callable that return the name that will be displayed in the sidebar
      display_title: ->(name) { name.split('::')[-1] },
    },
  ],
}