SystemUI: add more buttons to NavBar Tuner

<?xml version="1.0" encoding="utf-8"?>

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<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:systemui="http://schemas.android.com/apk/res-auto"

    android:layout_width="@dimen/navigation_side_padding"

    android:layout_height="match_parent"

    android:layout_weight="0"

    >

    <com.android.systemui.statusbar.policy.KeyButtonView

        android:id="@+id/menu_always_show"

        android:layout_width="@dimen/navigation_extra_key_width"

        android:layout_height="match_parent"

        android:layout_marginEnd="2dp"

        android:src="@drawable/ic_sysbar_menu"

        android:scaleType="centerInside"

        systemui:keyCode="82"

        android:visibility="visible"

        android:contentDescription="@string/accessibility_menu"

        />

    <com.android.systemui.statusbar.policy.KeyButtonView

        android:id="@+id/ime_switcher"

        android:layout_width="@dimen/navigation_extra_key_width"

        android:layout_height="match_parent"

        android:layout_marginEnd="2dp"

        android:src="@drawable/ic_ime_switcher_default"

        android:visibility="invisible"

        android:contentDescription="@string/accessibility_ime_switch_button"

        android:scaleType="centerInside"

        />

</FrameLayout>