Add edit banner button UI automated test + accessibility improvements

This commit adds an automated UI test to check if the edit banner button
UI is clickable and not hidden behind a top bar or another invisible
element.

It also improves accessibility support for some elements on login and
top bar.

Changelog-Changed: Improved accessibility support on some elements
Signed-off-by: Daniel D’Aquino <daniel@daquino.me>

damus/Components/Gradients/DamusBackground.swift

@@ -20,6 +20,7 @@ struct DamusBackground: View {
             .resizable()
             .frame(maxWidth: .infinity, maxHeight: maxHeight, alignment: .center)
             .ignoresSafeArea()
+            .accessibilityHidden(true)
     }
 }