add to nextcloud - file from url

My aim is to directly transfer a single file from a third-party server to a (my) nextcloud server.

### Is your feature request related to a problem? Please describe.
Currently surfing with an android device and find a interesting link/url of a larger single file e.g. with a new version of a manual (.pdf) or an .iso, .zip file on a third-party server and I need a copy of this file on my server for saving and sharing it with other nextcloud user
* A1. I have do download it with my browser on my smartphone
* A2. waiting till download is finished
* A3. upload the downloaded file to nextcloud
* A4. waiting till upload is finished
* A5. share the file with other nextcloud users
* (A6 clicking to the file in the nextcloud app it start download the file again to the android device now from the nextcloud server.)

Problem
- to many steps
- It costs mobile data traffic volume twice or three times * filesize
- once for download form external server
- and second for upload to nextcloud
- (A6 and a third time for download from nextcloud to android/media/com.nextcloud.client folder)

### Describe the solution you'd like
* B1. On nextcloud Android "add to nextcloud" -> from url
After enter or copy the url into the nextcloud android app "add to nextcloud from url" it starts an asynchronous download from the third-party server and save this in the selected nextcloud server folder.
* B2. (like A5) After download is finished the file can shared from nextcloud android app for other user with normal nextcloud ways.

### Describe alternatives you've considered
Copy the url as nextcloud note, go home, download at home and do steps A2 to A5

### Additional context
It's not always important to have immediately a local copy (A6) on the android device. It's more important to have a copy on the own server and to share it.