App polish part 2 (#1118)

- Fix sheet backgrounds in dark mode.
- Fix background colours for reaction buttons.
- Reply view layout.
- Update separator colours.
- Don't show sender name/avatar in DMs.
- Fix inconsistent line heights with formatted body text.
- Use plain text for reply
- Increase tappable size of collapsed state changes button.
- Blockquote layout and text colour.
- Tap to expand the topic in room details.
- Change the topic and security font size in room details.
- Add cancel button when inviting someone to an existing room.
- Reword Add Friends to Add People in start chat screen.
- Update compound.

ElementX/Sources/Screens/RoomScreen/View/TimelineItemMenu.swift

@@ -86,8 +86,8 @@ public struct TimelineItemMenu: View {
                 }
             }
         }
-        .background(Color.compound.bgCanvasDefault.ignoresSafeArea())
         .presentationDetents([.medium, .large])
+        .presentationBackground(Color.compound.bgCanvasDefault)
         .presentationDragIndicator(.visible)
     }
     
@@ -164,7 +164,7 @@ public struct TimelineItemMenu: View {
     
     private func reactionBackgroundColor(for emoji: String) -> Color {
         if item.properties.reactions.first(where: { $0.key == emoji }) != nil {
-            return .compound._bgReactionButton
+            return .compound.bgActionPrimaryRest
         } else {
             return .clear
         }