[Feature] Encryption about leaflet

[HrX03]

Update on this issue: encryption has been successfully implemented for local database and backup files, we still need to implement it for sync so keeping the thing open

[HrX03]

Encryption is wip on branch https://github.com/HrX03/PotatoNotes/tree/feature/encryption

[HrX03]

I was thinking about a master pin/password for notes, altho it is really hard to implement as of now (or at least I didn't find a proper way yet). For the note encryption thing, I should do it for every note and store an aes key or something that is user specific and that should be pretty easy to do