Part of ENG-7014
We need to query the store version that will be stored in synced_metadata. This will have three purposes:
- Address https://phab.comm.dev/D14780#inline-81137
- Being able to detect when backup is newer than an app and abort backup restore
- Store a backup store version somewhere and trigger backup restore after the user updates the app
- In the future, reading user-specific data we store in synced_metadata (e.g. currentUserInfo)
Depends on D14774