Feature: #92517 - Custom namespace for Extbase plugin enhancer

Description

The Extbase plugin enhancer for frontend routing allows to either set extension and plugin OR to set namespace. If extension and plugin were given, those were used.

However, the namespace option is automatically constituted by the extension and plugin options if it was not set intentionally. It is mainly used when overriding the custom extension and plugin options with a custom (usually shortened) namespace, so that the namespace is now always respected and preferred if all three options are set.

Impact

If all of namespace and extension and plugin options are configured, the namespace option is now preferred within the Extbase plugin enhancer.