Store OCR result in EXIF

[UweKeim]

Probably some day, Nextcloud will support searching within EXIF data.

When this feature will be implemented, I would love your app to (optionally, configurable) not write the OCR result to a PDF file, but instead store it inside the image itself as EXIF meta data, e.g. in the "remarks/comments" field or somewhere similar.

For non-EXIF images like PNG, the current PDF mechanism could be kept, or, optionally, could create a JPEG copy of the PNG and store the OCR result in that JPEG.