Show LanguageSwitcher if more than one culture

[hishamco]

Fixes #1024

[PavelVsl]

Sorry, but why in ControlPanel? Change it in LanguageSwitcher.razor

@if (_supportedCultures?.Count() > 1)  // HERE
{
    <div class="btn-group" role="group">
        <button id="btnCultures" type="button" class="btn btn-outline-secondary dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
            <span class="oi oi-globe"></span>
        </button>
        <div class="dropdown-menu" aria-labelledby="btnCultures">
            @foreach (var culture in _supportedCultures)
            {
                <a class="dropdown-item @(CultureInfo.CurrentUICulture.Name == culture.Name ? "active" : String.Empty)" href="#" @onclick="@(async e => await SetCultureAsync(culture.Name))">@culture.DisplayName</a>
            }
        </div>
    </div>
}

[hishamco]

Oops I thought that switcher button in the ControlPanel, it's my bad ;)

[hishamco]

@sbwalker could we merge this

[sbwalker]

I took a few days vacation with my family to end 2020 and I did not bring my laptop... I will return home tomorrow and will be able to catch up on all PR reviews, issues, etc...

[hishamco]

Take your time and enjoy with your vacation