[Feature request] Add "new tab" button to <hc:TabControl>

[jhm-ciberman]

Is your feature request related to a problem? Please describe. In our application we use the <hc:TabControl> control to let the user have different workspaces and perform different tasks in parallel like tabs in a web browser. We have a "+ New tab" button ("Nueva pestaña" in spanish) and when the user clicks the button a new tab is added to the ViewModel.

It would be nice to have a way to add an extra button in the tab strip like in Google Chrome, to let the user add a new tab.

This is our current setup (in case it matters)

<hc:TabControl 
    TabStripPlacement="Bottom"
    Grid.Column="1"
    TabIndex="-1"
    KeyboardNavigation.TabNavigation="None"
    x:Name="tabControl" 
    ShowCloseButton="True" 
    ShowOverflowButton="True"
    ShowScrollButton="True"
    IsDraggable="True" 
    IsScrollable="True"
    IsAnimationEnabled="True"
    IsTabFillEnabled="False"
    Validation.ErrorTemplate="{x:Null}"
    ItemsSource="{Binding Workspaces}"
    SelectedItem="{Binding SelectedWorkspace}">
    <hc:TabControl.ItemTemplate>
        <DataTemplate>
            <StackPanel Orientation="Horizontal" MaxWidth="200">
                <fa:IconBlock Icon="{Binding Page.Icon, FallbackValue=None}" FontSize="12" IconFont="Solid" Margin="0,0,8,0"/>
                <TextBlock Text="{Binding Page.Title}"/>
            </StackPanel>
        </DataTemplate>
    </hc:TabControl.ItemTemplate>
    <hc:TabControl.ContentTemplate>
        <DataTemplate>
            <ContentControl Content="{Binding Page}" Validation.ErrorTemplate="{x:Null}"/>
        </DataTemplate>
    </hc:TabControl.ContentTemplate>
</hc:TabControl>

Describe the solution you'd like An easy solution would be to add a <hc:TabControl.ExtraToolsTemplate> that can be customized via xaml. In this way would add our custom button to the end of the TabControl, and user who don't want that functionality would be unafected.

Something like this:

<hc:TabControl  ItemsSource="{Binding Workspaces}" SelectedItem="{Binding SelectedWorkspace}">
    <hc:TabControl.ExtraToolsTemplate>
        <DataTemplate>
            <Button Width="32" Command="{Binding AddWorkspaceCommand}">
                <fa:IconBlock Icon="Plus"/>
            </Button>
        </Button >
    </hc:TabControl.ExtraToolsTemplate>
</hc:TabControl>

This way developers will be able to add extra tools like "Add Foo tab", "Sort tabs" or other domain specific tools in the same DataTemplate.

Describe alternatives you've considered Currently I use a separate button at the top bar, but is not intuitive and unconventional.

Additional context Add any other context or screenshots about the feature request here.