Exclude offline and cached files from iCloud Backup

[jtagcat]

Re-open of #411
Open issue possibly related: #1447

Steps to reproduce

1. Mark files available as offline. Download files. (Shows up under Settings → Advanced → Delete files to free up space)
2. Try to backup iOS device: Settings → Apple ID → iCloud → iCloud Backup → Back Up Now (keeping in mind Nextcloud isn't excluded)
3. Backup fails due to insufficient iCloud backup storage

When testing, check ... → iCloud Backup → device → find Nextcloud in the list (size should be at most fewty MB).

Environment data

iPadOS version: 17.3.1

Nextcloud iOS app version: 5.1.0.7

Nextcloud version: 27.1.6

[marinofaggiana]

hi @jtagcat strange because are already set as isExcludedFromBackupKey

ios/iOSClient/Utility/NCUtilityFileSystem.swift

Line 170 in 0f24e37

// Directory Excluded From Backup