[BUGFIX] Web-View Module does not respect TCEMAIN.previewDomain

Bugfix for : https://forge.typo3.org/issues/61226

Added previewDomain in order to have Web-View functioning in the same way like Page-Preview does.
See also:
https://forge.typo3.org/issues/30889
https://forge.typo3.org/projects/typo3cms-core/repository/revisions/f2b91c8e50a4fe62045f125431b48a2aa18f59cd