Enhance look n' feel of StoryListView

[nathanbaleeta]

Taking into account the prototypes developed in consultation with the U-Report Product owner and testing team, modify the existing UI using the current data mapping structure to reflect the design on Figma

Carry out the following steps:

• Create a new branch from develop called ui-story-list-view. Hint: git checkout -b <new-branch> <existing-branch>
• Navigate to the file stories/StoryListView.dart
• Inside the ListView.builder, replace current widgets with appropriate widget classes from the flutter widget catalog
• Write tests for the improvements and save in in test/story_list_view_test.dart file.
• Commit the changes (as a single commit).
• Push changes to github. Hint: git push --set-upstream origin ui-story-list-view
• Open a pull-request.