Add IconExtension for WinUI

[tajbender]

Edit stub of IconExtension

[tajbender]

Initial commit. Builds fine.

e./: @dahall This is a Draft currently ⛑️

[tajbender]

@dahall: May I have an answer or your opinion:

For IconExtractor - Thx again 👍 - what lifetime would be the best?

• Should I use an own Instance of IconExtractor for every single folder / enumeration?
• Or should I use one Instance per lifetime, let's say of the Control - or even the App?

e./ regarding the lifetime I need for the Control itself:

• I create a single BitmapSource from each Icon Image I gather through IconExtractor (so, I use an own Cache for the Images after they have been extracted from the Shell32 Icon)
• I'll implement a small cache for those. I thought about using the original SysIconIndex as Indexer for this
• I'll implement an optional ViewMode, that only uses StockItems. Another one without ThumbNails
• For Details View, I'll use a Vanara.Windows.Shell.ShellDataTable

Thank you very much.