Add bool property to show/hide a MudProgressLinear progressbar

Is your feature request related to a problem? Please describe. I’d like a Visible or Hide bool property to show/hide a MudProgressLinear progressbar.

Describe alternatives you’ve considered

<MudProgressLinear Style="@($"display: {ShowElement(ActionIsBusy)};")" ...

@code{
    protected string ShowElement(bool show)
    {
        return show ? "block" : "none";
    }
}

[mikes-gh]

Yeah, good enough actually. Thanks.

Actually much better because

1. It doesn’t pollute the API with unnecessary props.
2. It avoids the performance hit of rendering a hidden component.

[Yomodo]

Yeah, good enough actually. Thanks.