Fix inconsistent closing of bottom panel in Image Viewer #14
Description
The problem
Currently, if bottom pane contents in ImageViewerPage can scroll, then SingleChildScrollView overrides scrolling behavior of the Pane and there is no way to close it, unless you grab the header, which is not the part of a scroll view mentioned above.
Expected behavior
Panel closes regardless of its contents when user swipes down on it.
Device information
All platforms
Additional context
Looks like we'd need to wait for the SlidingUpPanel to be updated or find our own solution, because using provided ScrollController does fix the issue, but messes up pagination...