MarkdownTextBlock sample should expose parsing/render options as checkboxes for sample exploration

[michael-hawker]

We should add a tracking issue to have the Markdown sample expose checkbox options for each of these settings properties so folks can see the behavior change in the output. (Though I think we'd have to make the control re-create the pipeline builder, I think they're all assumed to be set on initialization? Not 100% sure about that.) May be easier if we can switch to using the DependencyProperyGenerator later for all this stuff. :)

Originally posted by @michael-hawker in #674 (comment)

[michael-hawker]

Partially implemented in the sample side by @Arlodotexe in #674, but I think some more plumbing from the DependencyProperties to the pipeline builder needs to be done (i.e. recreate the markdown pipeline when any properties change). But I'm not 💯 sure, it can be tested easily now though.

[Arlodotexe]

Since the default values are different on the DP versus what's needed to demonstrate the examples upfront, the generated sample properties are currently only bound to the live editor.

We should look at splitting the live editor and the example into separate samples. They'd have the same generated sample options but different defaults.

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The changes needed to break MarkdownConfig into multiple DP on MarkdownTextBlock are being tracked in #611.

We can't easily bind to the properties on MarkdownConfig via the generated options pane. If the object is converted to multiple DependencyProperty, we can bind to each of them directly on MarkdownTextBlock instead of constructing a custom options pane with plumbing to construct a MarkdownConfig.