[SceneGraph LKG] Fix rapid clicking behavior + code cleanup

[iablaauw-MS]

This includes:

• Makes what happens if multiple pages are quickly clicked be more reasonable
  • The average case should not hit this
  • If clicking very quickly between two pages, we still play an animation but it targets the last clicked page
  • If clicking before the previous animation is quite finished it will still queue up another animation now
• Fixes some crashes and other issues if clicking rapidly (like getting stuck scaled up)
• Deletes a lot of dead code
• Cleans up some logic and naming in the DialogContentPage so that it's nicer to show off