This diff introduces the `ReactionTooltip` component that we be rendered whenever a user hovers over a reaction pill. This diff just introduces the component and subsequent diffs will handle the other parts to building a tooltip (calculating the tooltipSize and creating the hook that will create this tooltip)
Here is the linear [[ https://linear.app/comm/issue/ENG-3105#comment-a9acb5ac | thread ]] where we discuss what should the `ReactionTooltip` look like
Here is the design:
{F694448}
Depends on D8831