Clears 5 react-perf/jsx-no-new-* warnings in message.tsx by memoizing
image source objects, extracting an AssistantMessageBlockContainer for
per-block spacing, and moving todo list item rendering into a
TodoListItemRow subcomponent so each row memoizes its own style arrays.
The remaining 8 warnings in react-native-markdown-display render rules
are inherent to that library's rule API.
Mohamed Boudra
4dffd079eb