Refactor solution: Edit item hops navigation stacks, checks when leaving a form

Issue template

Description

Currently, the way to edit in item switches navigation stack from Pending Stack to Add Stack, which means that pressing back on a device will bring them to the AddScreen but that's not what we want. We want it to navigate them back to display the list of pending items.

This is not okay as it is confusing. If it means we need a new edit page screen that uses the same template components that add items does, then that's what we should do

• Warning message on back button to leave edit/add item of page

• What: not enough checks

• When: pressing back from editing or adding item

• How to fix: by adding alerts before adding page + create separate page edit different from add to simplify navigation stacks