message: Add TODOs for placeholder connection buttons
diff: Power BI window</TextBlock>
  </StackPanel>
  </Button>
  - <Button Grid.Column="1" Style="{StaticResource ConnectionButton}">
  + <Button Grid.Column="1" Style="{StaticResource ConnectionButton}"
  + Click="ConnectToDatasetClicked">
  <StackPanel>
  <Image
  Height="60"
  Power BI dataset</TextBlock>
  </StackPanel>
  </Button>
  - <Button Grid.Column="2" Style="{StaticResource ConnectionButton}">
  + <Button Grid.Column="2" Style="{StaticResource ConnectionButton}"
  + Click="OpenVertipaqFileClicked">
  <StackPanel>
  <Image
  Height="60"
  