nav: use back chevron in more places

Signed-off-by: William Casarin <jb55@jb55.com>

damus/Views/SearchView.swift

@@ -25,6 +25,8 @@ struct SearchView: View {
             .onDisappear() {
                 search.unsubscribe()
             }
+            .navigationBarBackButtonHidden(true)
+            .navigationBarItems(leading: BackNavBasic())
     }
 }