WebDeposit: class-based design refactoring
- Refactors WebDeposit to a class-based design to simplify data handling and allow easier customization.
- Adds storage abstraction layer for WebDeposit based on PyFilesystem.
- Adds file upload improvements including sorting of files.
- Adds webdeposit specific signals.
- Adds support for using field enclosures such as FieldList and FormField.
Co-authored-by: Konstantinos Ntemagkos <konstantinos.ntemagkos@cern.ch>
Co-authored-by: Jiri Kuncar <jiri.kuncar@cern.ch>