flutter-auto: Work-around for key keyboard event crash

flutter-auto: Work-around for key keyboard event crash

This is a work-around to still allowing key keyboard go through but
avoid passing an invalid messenger pointer to the flutter engine which
would ultimately crash flutter-auto. Initially we had a workaround to
avoid sending the key event altogether.

Bug-AGL: SPEC-5272
Change-Id: I4df9f298e26470b5edd039b31346e2dc8e788a01
Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/30509
ci-image-boot-test: Jenkins Job builder account
ci-image-build: Jenkins Job builder account
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Tested-by: Jenkins Job builder account
Reviewed-by: Joel Winarske <joel.winarske@gmail.com>