MLECO-6390: Refactor UI to remove redundant multiple app screen navigation

* Files have been refactored to be configured for just a single screen
* Redundant Navigation files have been deleted
* All references to navigation in composables and tests have been removed
* Tests have been refactored to use ScreenScaffold to build main screen

Signed-off-by: Olawole Abayomi-Owodunni <olawole.abayomi-owodunni@arm.com>
Change-Id: I5fabd48b6256b5f0476d24b6542c1bca179e4498