Feature request: Client side image resize

Hi,

I couldnt see any issues about this feature on grav or grav-plugin-admin repos.

Now almost photos size is bigger than _5MB_ and clients are doesnt use any photograph editors like photoshop to optimize and resize before upload.

**For example:**

to upload 10 photos with each _5 MB = 50 MB_
my connection speed is _25 Mbps_ (_~3 mb_ per sec download) / _2 Mbps_ (_~250 kb_ per sec upload)

so 10 photos uploading take time _~ 3.5 mins_ (this is so much for a client).

I think, client side image resizing feature should be on next version. What do you think about?