[MarkdownTextBlock] Turn everything in Config into DependencyProperty

[nerocui]

Describe the bug

Current implementation requires setting a Config object in either code-behind or view model. We should do that behind the scene and use DependencyProperty to forward all the settings from the consumer of the control to the internal config object.

Steps to reproduce

Use the control without the config and the control will crash.

<controls:MarkdownTextBlock Grid.Column="0"
                            Config="{x:Bind LiveMarkdownConfig, Mode=OneTime}"
                            Text="{x:Bind MarkdownTextBox.Text, Mode=OneWay}" />

Expected behavior

The control should work fine without any property being set. The developer should be able to set any property of config by using a dependency property instead of contracting the config in code.

Screenshots

No response

Code Platform

• UWP
• WinAppSDK / WinUI 3
• Web Assembly (WASM)
• Android
• iOS
• MacOS
• Linux / GTK

Windows Build Number

• Windows 10 1809 (Build 17763)
• Windows 10 1903 (Build 18362)
• Windows 10 1909 (Build 18363)
• Windows 10 2004 (Build 19041)
• Windows 10 20H2 (Build 19042)
• Windows 10 21H1 (Build 19043)
• Windows 11 21H2 (Build 22000)
• Other (specify)

Other Windows Build number

No response

App minimum and target SDK version

• Windows 10, version 1809 (Build 17763)
• Windows 10, version 1903 (Build 18362)
• Windows 10, version 1909 (Build 18363)
• Windows 10, version 2004 (Build 19041)
• Other (specify)

Other SDK version

No response

Visual Studio Version

No response

Visual Studio Build Number

No response

Device form factor

No response

Additional context

No response

Help us help you

Yes, I'd like to be assigned to work on this item.

[michael-hawker]

The default config should be there by default too, so if you don't do anything the control "just works"™️ out-of-the-box too. Saw this hit when trying to migrate from the old version.

[JimmyRespawn]

It'll be nice to use it without setting the config. In a situation like using it in Listview, MarkdownTextBlock is much easier to setup in v7.x. Also it would be nice to have OnImageClick return in v8 because it's easier to call in-box image viewer to see images inside markdown.