Implement base class & file structure.

Within this sub-task we want the base structure of the new Moodle 4.0 navigation to be implemented.

Add required functions for navigation_node.

Within this sub-task we need to add functionality to fetch navigation_node's to populate the navigation view by calling the settings_navigation functions that generates the system context nodes. It may be likely that we emulate a lot of the initialise() to populate this new navigation.

Acceptance criteria

• Using the example structure within this issue, create the required sub directories & files
• Using the example within this issue, implement the base functions within the primary navigation class
• Implement new magic method for primary navigation
  • $PAGE->primarynavigationview calls the function magic_get_primarynavview within lib/pagelib. This would create a new primary_navigation_view and triggers the initialise function within primary_navigation_view.
• Confirm the primary navigation elements in the design for the primary navigation are returned by the new class

Example structure:

/lib/classes
            /navigation
                       /views
                             /primary.php

Example class stub:

class primary_navigation_view extends navigation_node {
    // Sets up the view with basic settings and preparse it for use.
    public function __construct(array $properties) {}
    // Initialise the view based navigation based on the current context.
    public function initialise() {}
    /This function recursively scans nodes until it finds the active node or there are no more nodes.
    etc.....
}

Footnote:

This issue is slightly different from its counterpart within the secondary navigation series of issues. This issue rolls both the basic creation of files & classes with the implementation of the initialise function and population of the primary navigation view.