Breaking: #75942 - BigDocumentTemplate class removed 

See forge#75942

Description 

The following class has been removed:

\TYPO3\CMS\Backend\Template\BigDocumentTemplate

Impact 

Extensions that still use the removed class for their backend module won't work.

Affected installations 

A TYPO3 instance is affected if a 3rd party extension uses the removed class.

Migration 

Use \TYPO3\CMS\Backend\Template\DocumentTemplate instead.