To use Reanimated's new layout animations we need to add libdefs for the different animations. This diff just handles the `SlideInDown` and `SlideOutDown` layout animations along with all the necessary classes/types needed to support these layout animations. I will annotate inline with where the changes/types came from.
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Linear Task: [[ https://linear.app/comm/issue/ENG-2165/flow-type-reanimated-layout-animation | ENG-2165 ]]