* add new metadata functions to pdf engine interface
* add exiftool module with relevant test cases
* use exiftool to overwrite metadata in libreoffice
* use exiftool to overwrite metadata in chromium
* fix linter issues
* fix more linter issues
* more test cases for better coverage
* remove utils
* minor changes
* remove metadata from pdfoptions
* correct indentation
* read/write metadata one file at a time.
