[FEATURE REQUEST] Choose intervals between camera uploads scan

Is your feature request related to a problem? Please describe.
At the moment camera uploads are scanned every 15 minutes. Maybe it is not needed to trigger camera uploads so often.

Describe the solution you'd like
I would like to introduce the time between camera uploads scans, or at least have several options to choose: 15 minutes, 1 hour, 4 hours, 12 hours. This way we can reduce the battery drain if we don't need to upload files every 15 minutes.

Open to discuss: Save the value in DB or Preferences.

Additional context
At the moment, the time between camera scans are defined here

ACs

• New option in camera uploads. On the bottom. Sync interval, together with Last sync
• To decide: which is the best UI option to let user decide the interval. Four default options (15mins, 1h, 4h, 24h)
• Default: 15 mins
• Separate for videos & pictures
• Check if a delay is needed to avoid race conditions in execution. Worker is enqueued, and we need a little time to setup the feature before the work is triggered.

TASKS

• Research (if needed)
• Create branch feature/feature_name
• Development tasks
  • Implement whatever
  • ...
• Code review and apply changes requested
• Design test plan
• QA
• Merge branch feature/feature_name into master

PR

• App
• Library (if needed)

Start with owncloudApp/src/main/java/com/owncloud/android/workers/CameraUploadsWorker.kt around line 290 to understand the current 15-minute schedule. Then trace the camera uploads settings UI and decide how the interval is persisted for pictures and videos. Done means the UI offers the specified intervals, keeps 15 minutes as the default, and schedules scans accordingly without race conditions.