SystemUI: add left and right virtual buttons while typing

Co-authored-by: Bruno Martins <bgcngm@gmail.com>
Co-authored-by: Danny Baumann <dannybaumann@web.de>
Co-authored-by: LuK1337 <priv.luk@gmail.com>
Co-authored-by: Oliver Scott <olivercscott@gmail.com>
Co-authored-by: Sam Mortimer <sam@mortimer.me.uk>
Co-authored-by: Steve Kondik <steve@cyngn.com>
Change-Id: Iea446443d33ff305765e47c86523b619676116ac