Correct/Remove Overlay settings sections for IgxToast, IgxSnackbar

[RivaIvanova]

Description

The documentation states that both components use "Overlay Settings to control the position of its container. The default settings can be changed by defining Custom OverlaySettings and passing them to the open() method."

public customSettings: OverlaySettings = {
    positionStrategy: new GlobalPositionStrategy(
        { 
            horizontalDirection: HorizontalAlignment.Left,
            verticalDirection: VerticalAlignment.Top
        }),
    modal: true,
    closeOnOutsideClick: true,
};

toast.open(customSettings);
snackbar.open(customSettings);

Toast Overlay Settings docs & Snackbar Overlay Settings docs.

However, none of the open methods accept OverlaySettings as a parameter. (toast open(), snackbar open())

// toast
public override open(message?: string, settings?: PositionSettings) {
   ...
}

// snackbar
public override open(message?: string) {
   ...
}

Related to IgniteUI/igniteui-angular#14934