Add additional gestures when viewing individual photos

[jasonliu--]

Is your feature request related to a problem? Please describe.
When viewing an individual photo, certain gestures that seem to be standard in other photo apps don't seem to exist.

Describe the solution you'd like
When viewing a photo, gestures that appear to be missing are:

• Swiping down when you are fully zoomed out takes you back to the page that shows the thumbnails of the current album. (It's the equivalent to tapping the "< Back" button.)
• Pinching together with two fingers when you are fully zoomed out will also take you back to the page that shows the thumbnails of the current album. (Again, it's the equivalent to tapping the "< Back" button.)
• Swiping up when you are fully zoomed out brings up the metadata info of the photo. (Which I assume would be the info that is discussed in Show Exif/other metadata, especially keywords/tags #349.)

Describe alternatives you've considered
N/A

Additional context
Adding these gestures when viewing an individual photo would bring the Piwigo mobile app in-line with other photo apps.