Allow filename pattern selection. Duplicate file upload.

### Actual behaviour
Autoupload uploads images/video files to nextcloud server keeping the same name.
So if delete after upload option is selected android will reset DSC_XXXX file seq from the most recent.
Example files in DCIM folder. DSC_0001, DSC_0002.
I take a photo, filename is DSC_0003.
Nextcloud detects it, uploads, deletes.
Next time i take the photo again and file name again is DSC_0003 => clash at autoupload.

### Expected behaviour
It would be nice to name files at upload like it is done in iOS version or in previous version like 1.4.0-something
Photo date time taken DSC seq number.
Or give option to the user to choose how to name it.

### Steps to reproduce
1. setup autoupload the way it delete photo after it is taken
2. take photo, wait autoupload to upload it
3. take another photo, it will not get uploaded.

### Environment data
Android version: 4.4.4

Device model: xperia Z2/D6503

Stock or customized system: rooted

Nextcloud app version: dev latest 07/27

Nextcloud server version: 11.0.0

### Logs
#### Web server error log
```
Insert your webserver log here
```

#### Nextcloud log (data/nextcloud.log)
```
Insert your Nextcloud log here
```
**NOTE:** Be super sure to remove sensitive data like passwords, note that everybody can look here! You can use the Issue Template application to prefill some of the required information: https://apps.nextcloud.com/apps/issuetemplate