[LocalBackup] Remove duplication and Messenger access from Backup functions

[jrainville]

Description

See comments here: status-im/status-go#6722 (comment)

For the local backup "services", I had to duplicate some code from the Messenger to make it work.

Some of that code will be removed as part of #18123, but some is still gonna be needed for the Sync (paired devices), so we need to move that to a common place.

Thankfully, those functions don't rely on anything related to the Messenger, we can just pass properties and get a result.

Finally, the Accounts Service backup currently calls the Messenger directly. It has access to it, so it's not the end of the world, but it would be cleaner to do like above and extract the functions to a common util and make it separate from the messenger.