Breaking: #107403 - Remove LocalPreviewHelper + LocalCropScaleMaskHelper 

See forge#107403

Description 

The helper classes for Preview and CropScaleMask (CSM) for generating images blocked a proper unification of the File Abstraction Layer Image Processing API.

The two helper classes \TYPO3\CMS\Core\Resource\Processing\LocalPreviewHelper and \TYPO3\CMS\Core\Resource\Processing\LocalCropScaleMaskHelper have now been removed, as their functionality has been merged into \TYPO3\CMS\Core\Resource\Processing\LocalImageProcessor .

The helper classes existed due to legacy reasons, but were never intended to be Public API.

Impact 

Any code that extends or references \TYPO3\CMS\Core\Resource\Processing\LocalPreviewHelper or \TYPO3\CMS\Core\Resource\Processing\LocalCropScaleMaskHelper will result in PHP fatal errors.

Affected installations 

Installations with custom extensions that extend or reference the \TYPO3\CMS\Core\Resource\Processing\LocalPreviewHelper or \TYPO3\CMS\Core\Resource\Processing\LocalCropScaleMaskHelper will cause PHP fatal errors.

The helper classes were meant to be internal, but were not declared as such. Implementations utilizing the helpers outside the use of the LocalImageProcessor should be rare.

Migration 

Remove any references to \TYPO3\CMS\Core\Resource\Processing\LocalPreviewHelper or \TYPO3\CMS\Core\Resource\Processing\LocalCropScaleMaskHelper from your code.

Utilize the \TYPO3\CMS\Core\Resource\Processing\LocalImageProcessor processor directly instead or implement a custom image processor that is executed before this processor with custom functionality.