Implement EZP-20231: Cluster support in FieldTypes

This PR implements cluster support for binary FieldTypes (Image, BinaryFile, Media) by means of a LegacyFileService.

Tasks:
- [x] Refactor the FileService
- [x] Create LegacyFileService
- [x] Adapt FieldType: BinaryBase
- [x] Adapt FieldType: Image
- [x] Adapt FieldType: BinaryFile
- [x] Adapt FieldType: Media
- [x] Refactor MetaData handling
- [x] Implement ImageSize metadata handler
- [ ] Fix the `storeFieldData` / `copyLegacyField` callbacks in the Field Handler. Candidate: https://github.com/ezsystems/ezpublish-kernel/pull/235.

Note: there currently is a bug/limitation in the refactoring introduced in https://github.com/ezsystems/ezpublish-kernel/pull/170 that causes some IntegrationTests to fail. This is due to `storeFieldData()` being called instead of `copyLegacyField` when copying data from a previous version.