Increase BigTest coverage for ui-data-import application

The aim of the story is to increase automated test coverage for the existing for ui-data-import application code to 80+ %, thus creating the basement for further test writing.

Keep the work time-boxed to 2-3 points per sprint. For new stories, clone UIDATIMP-126.

What to cover:

• landing page
• file extension page
• settings page
• job profiles page

What will be done:
Create boilerplate test setup for the specified pages (interactors, tests)
Mock backend for the happy path scenario
Write tests that check that pages render without errors
Handle available code smells (2 cases now)

NOTE
This umbrella does not cover automated testing to for new code, only to work down the debt for existing code.
For new code: testing will
1) be part of the functionality's UIDATAIMP story, if the effort is not large or
2) be a new UIDATAIMP story, if the addition of testing to the functionality's story will make that story too large.
Our expectation is that testing for new code will be completed at approximately the same time as the functionality, and we will not continue to add to the existing testing debt.