[native] Disable Delete chat button when trying to delete a chat and the password input is empty

Summary:
Disable the button if the password is empty, and also handle the
enter button from being pressed within the input field and make sure not
to attempt to disable the thread.

Test Plan:
Tested both cases where the button becomes unclickable and
pressing enter within the input field should not submit the contents of
the field

Demo:

Reviewers: atul, ginsu, abosh

Reviewed By: atul

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D5320