[native] Added animation to the edit box when entering/leaving edit mode

Summary: Added appearning and disappearing animation to the edit message box in edit mode.

Test Plan:
Run the app. Check the animations.

Videos: (might look a little bit laggy on simulator, didn't have access to physical devices)

iOS:

Android:

Reviewers: ashoat, inka, michal

Reviewed By: ashoat

Subscribers: tomek, atul

Differential Revision: https://phab.comm.dev/D7790