Equalizer: UI and UX fixes and improvements

Fix constraints constants in landscape for VideoPlayerViewController
Improve cancel button in EQ to be clearer (hidden by default, shown only when needed)
Add a titleLabel with accessoryViews in popup for better UX
Swap EQ and sleep timer in the ActionSheet for consistency
Fix button and arrows for larger devices on SpoilerButton
Fix sliders in right to left languages
Fix constraint errors