Force upload of movies and videos already present on the phone

Actual behaviour

The client doesn't upload old pictures and videos present on the phone.

Expected behaviour

It should be some way to trigger the upload of the photos and videos already present on the phone before installation of the client.

Steps to reproduce

1. shoot some picture on the phone
2. shoot some videos on the phone
3. download the oC Android client

Environment data

Android version: 6.0

Device model: MotoG 3rd gen

Stock or customized system: stock

ownCloud app version: 2.0.1

ownCloud server version: ownCloud 9.0.4 (stable)

EDIT 2021:

• Add an option when enabling camera uploads to decide whether sync is done from scratch or from now on. Sync also old stuff?. (question: would it be posible to persist which device locations were synced somewhen? in order to do it only once)
• To take in account if the option is checked
  • Performance (check with huge amount of files > 1000 ). System will decide priorities to queue, not in our hands. User should be warned about the use of bandwidth and/or storage.
  • Quota. Check first if the quota is enough. Worker can do it. In case quota exceeds the remaining storage, user is warned that available storage is not enough. User will have to decide:
    - Ignore the warning and go on: files will start to upload till storage is full. Remaining files will be enqueued with a proper error (insufficient quota). From here on, same behaviour as the current one.
    - Abort sync: nothing will be done because user does not want to sync some files and lose other ones.
    Nice to have: tell him how much extra space will be needed to do the sync.
• Behaviour will be the same as before after enabling: new stuff will be enqueued and uploaded.
• Danger: disabling and re-enabling the feature: cause of duplications. (question in first point)

Start with the camera-upload enable flow and the existing queue/worker behavior described in the issue. Trace how device locations are selected and remembered, then determine how the opt-in choice, large batches, bandwidth warnings, quota checks, and re-enabling behavior should work. Done means old media can be intentionally synced without unintended duplicates and with the stated quota outcomes.