feat: Added plugin config option in browser plugin

[Aerex]

Context: Allows creating a customization configuration page for plugins.

The following steps must be done to configure the page.

• The plugin must implement the getConfigBrowser method. The method should return a raw html page.
• Update the plugin metadata with config => true

    function getPluginInfo() {
        return [
          'name'        => $this->getPluginName(),
          'description' => 'The plugin provides synchronization between remote storages and iCal events',
          'link'        => 'https://git.aerex.me/Aerex/baikal-storage-plugin',
          'config'      => true
        ];
      }
  

After the following steps are made A cog wheel will appear besides the documentation icon