Draft: Export refactor

• Mutualize meminfo between exports
  • Make work Aidge memory manager (currently a simple version is used ...)
  • Add meminfo in export_node ?
• Create ExportGraph
  • Better handle input/ouput
  • Add is_output and is_input attribute in ExportNode
  • Generate export with different backends (future ...)
  • Generate mem manager and scheduling
• Refactor Export node
  • Add a dictionnary attributes to stack all the attributes desirable for the export
  • Add function to be agnostic from data form (get_input_channel etc ...)
• Change key for selecting an ExportNode (backend + dataformat ...)