ComponentInstaller creates always new components on plugin reinstallation

[mitelg]

The function createOrUpdate() of the ComponentInstaller class is used in a plugin's install() to create custom shopping world element (as described here https://developers.shopware.com/developers-guide/custom-shopping-world-elements/#registering-a-new-element).

The problem is, each time the plugin is reinstalled, the shopping world element is removed from the shopping world and a new copy of the element is created. This results in multiple copies of the element in database and in shopping worlds designer and the element in the shopping world has to be added again.

The function createOrUpdate() should first check if the element is present in the database and create it only if it isn't.