Option to defer local deletion of the latest file to maintain camera app filename sequencing

### Is your feature request related to a problem? Please describe.
There are camera apps out there that generate file names with a sequential counter. For any new photo, the number to be used is derived from the existing content of the photo storage directory. Configuring nextcloud to auto-upload and delete/move local files on that directory makes a lot of sense, but after all files are removed, the camera app would start with something like DSC_0001 or so again. In practice, it is a lot more unpredictable, depending on timings of upload/deletion, restart behaviour of the camera app, etc.
You would end up with hundreds of different photos named like DSC_0001 (xyz), plus you have to confirm manually that you want to keep all of the duplicately named files.

### Describe the solution you'd like
Defer deletion of the _newest_ file (according to its creation time stamp) from the configured auto-upload directory even after it was successfully uploaded, until a newer file is available. This behaviour might be configurable, the configuration might be pre-set to on or off based on smart analysis of the directory's current content or on known devices or camera apps.

### Describe alternatives you've considered
Replace such camera apps - however, camera apps are bundled with devices to make the best out of the respective hardware features.
Auto-rename files with a sequential number pattern to a high-resolution timestamp pattern. However, detection of sequential number patterns might be a hard problem.

### Additional context
n/a