Settings: Add toggle for heads up notifications

    <string name="high_touch_polling_rate_title">High touch polling rate</string>

    <string name="high_touch_polling_rate_summary">Increase touchscreen polling rate</string>

    <!-- Heads-up -->

    <string name="heads_up_notifications_enabled_title">Heads-up</string>

    <string name="heads_up_notifications_enabled_summary">Display priority notifications in a small floating window</string>

    <!-- High touch sensitivity -->

    <string name="high_touch_sensitivity_title">High touch sensitivity</string>

    <string name="high_touch_sensitivity_summary">Increase touchscreen sensitivity so it can be used while wearing gloves</string>

            android:summary="@string/notification_assistant_summary"

            settings:controller="com.android.settings.notification.NotificationAssistantPreferenceController"/>

        <!-- Heads up -->

        <lineageos.preference.GlobalSettingSwitchPreference

            android:key="heads_up_notifications_enabled"

            android:order="24"

            android:title="@string/heads_up_notifications_enabled_title"

            android:summary="@string/heads_up_notifications_enabled_summary" />

        <!-- Notification lights -->

        <lineageos.preference.LineagePartsPreference

            android:key="notification_lights"