Include sticker collection in account backup

Feature Proposal
1

Expected behavior

The sticker collection is included in the account backup.

Actual behavior

The sticker collection is not part of the account backup.

Explanation

I think it would make sense to save the sticker collection together with all other data in the backup. Some users are unaware that their stickers are not included and may suffer data loss.

2

stickers are not yet managed by deltachat core, that is the reason for it.