[Feature Request] Save User Data not only for User 0

[MichaelZ4714]

Is your feature request related to a problem? Please describe it.
On my device I have an additional user (work profile, in my case its user 11). This data is not included in backup. I also need that data.
Neo Backup crashes on start when copied to work profile using Insular(https://f-droid.org/en/packages/com.oasisfeng.island.fdroid/, fork of Island).

Describe the primary solution
Tha data of additional users is also put into the backup. It is automatically restored if that user number exists on that device, otherwise a warning will be shown.

Describe alternative solutions, if any
The backup of additional users could be controlled in the options.

Screenshots

System Information (please complete the following information):

• Device: independent
• Android Version: independent
• ROM: (AOSP, MIUI, OOS...) independent
• App Version: 8.0.2

[machiav3lli]

Further discussion at #795