[LocalBackup] SPIKE to check that importing from a file is doable

[jrainville]

[jrainville]

I managed to create a POC in the backend that shows we can indeed put backups in a file, encoded it and then decode it later and extract the data to a new instalation.

The PR is here: status-im/status-go#6669

I will now create more issues for the remainder of the work and seek opinions on the best way to progress