Add MasonryGridView to the Gallery

[Aaliya-Ali]

Proposed Changes

• Replaced the GridView with a MasonryGridView in the Gallery Screen

Please check that the PR fulfills these requirements

• Set a 100 character limit in your editor/IDE to avoid white space diffs in the PR
• Tests for the changes have been added (for bug fixes / features)
• Added yourself to AUTHORS.md

[rolandgeider]

FYI, I have approved the PR so that it will count towards hacktoberfest

[Aaliya-Ali]

Thanks for approving my PR. Does an approved PR mean it is getting merged for sure?
Actually, I want to make an actual contribution(although small), not just for the sake of completing Hacktoberfest. So, I wanted to make sure it gets merged. Let me know if there's anything I can do to have it merged.

[rolandgeider]

You already did contribute :)

Basically what we could still figure out are the tests. It also shouldn't be that we invest three times as much fixing this than in implementing the feature so if we can't come up with any ideas, we can just mark the test as skipped and open an issue so this doesn't get lost

[Aaliya-Ali]

Makes sense. Thanks again :)

[rolandgeider]

All green now, thanks!