[BUGFIX] Clarify exception for missing ViewHelper

[s2b]

Currently, the exception message for a missing ViewHelper includes the "fake component namespace" without the ViewHelper suffix. This makes the exception hard to understand, since the problem is probably not related to a missing component but to a missing ViewHelper.

before:

The ViewHelper "vac:asset.vite" could not be resolved. Based on your spelling, the system would load the class "Praetorius\ViteAssetCollector\ViewHelpers\Asset\Vite", however this class does not exist.

after:

The ViewHelper "vac:asset.vite" could not be resolved. Based on your spelling, the system would load the class "Praetorius\ViteAssetCollector\ViewHelpers\Asset\ViteViewHelper", however this class does not exist.