UI: Refine YouTube dialog

- Make the settings a scroll area. This makes it work on smaller screens and
if more items are added in the future, the dialog doesn't get bigger.

- Made the additional settings label bold to distinguish better.
Also removed the colon, as I felt it wasn't needed because it is
now bold.

- Made the margins consistent between the settings and events pages

- Made the scrollbar show only when needed in the events page

- Moved the remember settings checkbox to the top of the settings because
it just seems better to be there.

UI/data/locale/en-US.ini

@@ -1357,7 +1357,7 @@ YouTube.Actions.MadeForKids="Is this video made for kids?*"
 YouTube.Actions.MadeForKids.Yes="Yes, it's made for kids"
 YouTube.Actions.MadeForKids.No="No, it's not made for kids"
 YouTube.Actions.MadeForKids.Help="<a href='https://support.google.com/youtube/topic/9689353'>(?)</a>"
-YouTube.Actions.AdditionalSettings="Additional settings:"
+YouTube.Actions.AdditionalSettings="Additional settings"
 YouTube.Actions.Latency="Latency"
 YouTube.Actions.Latency.Normal="Normal"
 YouTube.Actions.Latency.Low="Low"