[RN0.66] 39/n: Fix KeyboardInputHost BaseProps type
Summary:
ChatInputBar can render KeyboardInputHost with a textInputRef set to null.
This type error was caught as part of the Flow upgrade.
Test Plan: Flow
Reviewers: palys-swm, atul
Reviewed By: palys-swm
Subscribers: benschac, Adrian, karol-bisztyga
Differential Revision: https://phabricator.ashoat.com/D3020