Device Wallpaper Uploads

**Is your feature request related to a problem? Please describe.**
I am managing several dozen OU's with custom wallpapers. These sometimes need to be changed and it is a pain to go in and manually edit them one by one in the Google Admin GUI. You have to upload the the new JPG, for each OU which is very time consuming.

**Describe the solution you'd like**
It would be fantastic to be able to upload the JPG once and then be able to call upon the same URI over and over to update the OU's. This way I do not have to update dozen's of OU's with the JPG. Upload it once and then call on it again and again.

**Describe alternatives you've considered**
Another option would be to manually upload it to a single OU and then copy the policy from one OU to another OU with the wallpaper carrying over.

**Additional context**
Add any other context or screenshots about the feature request here.