Feat : show size of space before start syncro

## Expected

- Can seen size of the remote space before start synchronization.
- Can seen local size before synchro, to know if it is a good idea to start syncro now

# Use case

- I want to synchronize space locally but I don't know if I need a very good internet connection to do that or not (depend of space size)
- I have done some modification locally and I need to know the difference size of space locally and remotelly, to know if it is a good idea to start synchronization now, or if it is better to start this at another moment. This is just an information, but if I not seen big diffential size, I can start without risk to stop syncro.