Update strings with UX mocks

    <!-- Message shown during face enrollment when the face is too similar to a previous acquisition [CHAR LIMIT=50] -->

    <string name="face_acquired_too_similar">Too similar, please change your pose.</string>

    <!-- Message shown during acqusition when the user's face is turned too far left or right [CHAR LIMIT=50] -->

    <string name="face_acquired_pan_too_extreme">Please look more directly at the screen.</string>

    <string name="face_acquired_pan_too_extreme">Turn your head a little less.</string>

    <!-- Message shown during acqusition when the user's face is tilted too high or too low [CHAR LIMIT=50] -->

    <string name="face_acquired_tilt_too_extreme">Please look more directly at the screen.</string>

    <string name="face_acquired_tilt_too_extreme">Turn your head a little less.</string>

    <!-- Message shown during acquisiton when the user's face is tilted too far left or right [CHAR LIMIT=50] -->

    <string name="face_acquired_roll_too_extreme">Please straighten your head vertically.</string>

    <!-- Message shown during acquisition when the user's face is obscured [CHAR LIMIT=50] -->