Breaking: #413 - Remove ViewHelpers for Variables

See Issue #413

Description

The extension does not use the ViewHelper for variables. In TYPO3 a ViewHelper is available for setting and reading variables. So the own implementation can be removed without disadvantages.

Affected Installations

All installations using \Extcode\Cart\ViewHelpers\Variable\GetViewHelper or \Extcode\Cart\ViewHelpers\Variable\SetViewHelper in templates or partials.

Migration

Replace all occurrences in the templates.