web: add unit test to cover `Panel` location change
Created by: valerybugakov
Changes
- Added unit test to cover location mutation on tab change in the
Panel
component.
Follow up for https://github.com/sourcegraph/sourcegraph/pull/22600.
Created by: valerybugakov
Panel
component.Follow up for https://github.com/sourcegraph/sourcegraph/pull/22600.