Improve download multiple images UX

### Your use case

#### What would you like to do?
download multiple images in a room to my phone
#### Why would you like to do it?
Because someone sent a collection of images that I all want
#### How would you like to achieve it?
Press one button only for each image I download
Or even better: have the option to select a group of images and press download.

### Have you considered any alternatives?

The current solution is to press the (i) button in the top right corner and the download for each image that I want to download.
With the new media swipe feature that would be already good if I there would be a download button in the top right corner (as there was at some point in time)

### Additional context

I think, the download and open in external app buttons could be swapped.
I dont see a situation where i would like to open multiple images after each other externally quickly. So i dont see an issue with pressing two buttons to get it opened externally.
For downloading i can see how one wants to do that as a batch operation. So making it easier to access is useful.

### Are you willing to provide a PR?

No

No files, tests, or entry points are named. Start by locating the Android media-swipe flow and the existing download and external-app actions; agree whether the target is one-tap downloads, group selection, or both, then verify the chosen interaction works for multiple images in a room.

Written by the indexing model from the issue text.