Refactor the FileReaderTasks to abstract the input file type

[shavounet]

Feature description

• ease the definition of new file type that can be read/written
  • old interface are not flexible enough for all use cases
• add a new XMLReaderTask

Implementation proposal

• new namespace File (maybe one day, a separate bundle & ditch the old interfaces ?)
• based on SplFileObject ?
• separate File manipulation and Resource manipulation using composition instead of inheritance
• interfaces : readable / writable / readableStream / writableStream / seekable ?
• file types : csv / json / json_stream / xml
• test compaibility with flysystem ?

PR requirements

• Documentation
• Unit tests
• Breaking changes : yes (minor, on FileInterface ? add a new interface & depreciate the old one ?)