Maintenance: Add mandatory field offset markers /* XXXX */ and assertions to UI headers
Batch #1065 by ragnarok-clanker: no function's compiled code changes; checked with 92 compiled unit(s), including every includer of Source/UI/Buttons/UIBmpTextButton.h, Source/UI/Chat/ChatNotifications.h, Source/UI/Cooldowns/CooldownDrawing.h, Source/UI/Cooldowns/CooldownState.h, Source/UI/Edit/ItemTagRetirement.h, Source/UI/Layout/SnapRectangle.h, Source/UI/Lists/UIListBoxEx.h, Source/UI/MiniPartyGrid.h, Source/UI/Party/UIAdvenPartyBoardWnd.h, Source/UI/Party/UIRequestJoinPartyMgr.h, Source/UI/Shop/PriceColor.h, Source/UI/Shortcuts/ShortcutCooldowns.h, Source/UI/Shortcuts/ShortcutGrid.h, Source/UI/Text/TextMarkup.h, Source/UI/Text/UITransBalloonText.h, Source/UI/Window/FrameTextCache.h, Source/UI/Window/UIWindow.h, Source/UI/Window/WindowAncestry.h, Source/UI/Window/WindowRegistration.h.