Ensure the back gesture tutorial icon renders correctly for RTL

This change adds RTL support for the back gesture icon on the main menu
of the gesture tutorial menu. In RTL mode, it was previously rendering
in the middle of the screen.

Flag: ENABLE_NEW_GESTURE_NAV_TUTORIAL
Fix: 309564541
Test: ran the tutorial in RTL mode in different form factors.
Change-Id: I24def01ed205355ced23060068ddd74af61134ab