Expanded the SampleAppCustomized project

[JD-Howard]

Since there really isn't any documentation and I wound up digging into this enough to mostly understand the customization. I figured I would update the SampleAppCustomized project to show more of what can be done.

MainWindow.xaml/.cs

• Added style customization and showed a method of injecting them while re-styling the MarkdownViewer.
• Changed the Button to a ToggleButton so it now has: All Supported, Default & Customized states.

Customized.ColumnScalingTableRenderer.cs

• Largely a copy of the TableRenderer, but I did use #regions Customization to help show the diffs.
• This specific implementation forces header rows to center & does a distribution scale on the column widths.

Customized.WpfRenderer.cs

• I changed the concept of this around. Instead of it constructing custom renderers, it just "uses" the ones it is given.

Customized.MarkdownViewer.cs

• Basically does the same work but in a different order and accounts for the addition presentation state.
• I don't believe that forced update to UCRootPath is still required, but I moved/left it there since I am unfamiliar with the problem it was addressing.