* Remove perspectives switch from navigation.
* Remove no longer needed filtering of navigation items, based on active perspective.
* Route to default welcome page instead of perspective specific page on start page.
* Remove action to switch perspective from quick jump modal.
* Remove perspective info from telemetry events.
* Remove not needed imports
* Remove perspectives context.
* Remove mocking of perspectives in tests.
* Cleanup
* Fixing tests
* Adding changelog.
* Extend `UPGRADING.md`.
* Update tests
* Cleanup
* Improve changelog