Add selection assertions to cherry-pick tests

We are about to change the selection behavior when cherry-picking, and it's good
to have tests that document in what way it changes in the next commit.

pkg/integration/tests/cherry_pick/cherry_pick_range.go

@@ -70,7 +70,7 @@ var CherryPickRange = NewIntegrationTest(NewIntegrationTestArgs{
 				t.Views().Information().Content(DoesNotContain("commits copied"))
 			}).
 			Lines(
-				Contains("four"),
+				Contains("four").IsSelected(),
 				Contains("three"),
 				Contains("two"),
 				Contains("one"),