[New architecture] UI tests for public sharing, using whole flows

[davigonz]

The tests already developed within the new architecture cover UI in an isolated way for each fragment and tests that take advantage of whole flows when sharing, e.g. create public share and see it in the shares list, would be needed as well.

TASKS

• Research (if needed)
• Create branch feature/feature_name
• Development tasks
  • Implement whatever
  • ...
• Code review and apply changes requested
• Design test plan -> https://github.com/owncloud/QA/blob/master/Mobile/Android/Templates/Sharing%20Flow%20tests.md
• QA
• Merge feature branch into master

PR

• App: [New architecture] Whole flow tests for sharing #2558