Add unpacked database size in snapshot artifact

[jpraynaud]

Issue

Add the size of the unpacked database in the snapshot artifact and use it to check the available size by the client more accurately

To do

• [ ] Compute and store the unpacked database size in the snapshot artifact
• [ ] Adapt disk space check mechanism in the snasphot download command of the client
• [ ] Display this information in the snasphot show command of the client