[TASK] Force page UID for ConfigurationManager when editing a page

Fixes: #46

This change works around a limitation in the Extbase BackendConfigurationManager which is not capable of detecting the page UID from the special "editconf" global array containing the actual page UIDs being edited. Since there is no "raw" page UID in the URL, Extbase returns the first detected root TS template (as is the current fallback behaviour).

By forcibly overriding GET.id Extbase will immediately detect and use this ID - making TS resolve operations work as expected when editing pages.

Editing content elements is not affected by this Extbase lack of consideration - when editing tt_content, GET.id exists.