Automatically set BackendMenu context from controller path

[sephyld]

Closes #1269

I've added the three protected attributes $author, $plugin and $sideMenuItemCode in order to set the backend menu context in the base controller class. As per linked issue's description, I'm setting the values for these attributes during class generation.

The only reason left for the constructor to be overridden by the created controller was the chance of using the --sidebar option when using the create:controller artisan command. Passing this option resulted in setting the boolean sidebar property for it to be used in the template scaffold file. If this property is true the controller assigns the value compact-container to the $bodyClass attribute.

In order to get rid of it I thought it would be better to set the same value for the $bodyClass outside the constructor

[LukeTowers]

@sephyld we could probably set those values from the namespace of get_class($this) inside of the run method after the action has been run but before the view is rendered if BackendMenu::getContext() doesn't return anything (or just set it by default in the run method before the action is run so that it can be overridden). That way devs don't have to provide any values at all if they have the default approach of 'author.plugin.controller.action` for menu context but can still override it if for some reason they need a different backend context (usually because they're providing a controller that is going to be injected into another context's navigation menu, i.e. a Comments plugin that extends the Blog plugin and adds the Comments controller to the blog main menu item).

[sephyld]

@LukeTowers hi

I see. I was thinking about something like this, please let me know if I'm on the right track

        // run method
        // [...]
        /*
         * Set the admin preference locale
         */
        BackendPreference::setAppLocale();
        BackendPreference::setAppFallbackLocale();

        /*
         * Set the navigation context
         */
        $this->setNavigationContext();

        /*
         * Execute AJAX event
         */
        if ($ajaxResponse = $this->execAjaxHandlers()) {
            $result = $ajaxResponse;
        }
        // [...]

    protected function setNavigationContext(): void
    {
        $context = \BackendMenu::getContext();
        $fullClassNameArray = explode('\\', get_class($this));

        $author = $fullClassNameArray[0];
        $plugin = $fullClassNameArray[1];
        $className = $fullClassNameArray[count($fullClassNameArray) - 1];

        $owner = $context->owner ?? "$author.$plugin";
        $mainMenuCode = $context->mainMenuCode ?? strtolower($plugin);
        $sideMenuCode = $context->sideMenuCode ?? strtolower($className);

        \BackendMenu::setContext($owner, $mainMenuCode, $sideMenuCode);
    }

This way we cuold get rid of the $author, $plugin and $sideMenuItemCode protected attributes. Devs could simply override the setNavigationContext method doing something like this in the controller classes

    protected function setNavigationContext(): void
    {
         \BackendMenu::setContext("AnotherAuthor.AnotherPlugin", "anotherplugin", "items");
    }

or if \BackendMenu::setContext is called in the constructor the getContext call will return the previously given values.

Does it check out?

[LukeTowers]

That's perfect @sephyld, thanks very much! I've implemented it in 5d0b9ca as a part of #1312