Updating project / item template icons and descriptions

[niels9001]

ORIGINAL PR (with comments + feedback): #4924

Closes: #4923

The following changes are included:

Updates to the Windows App SDK and WinUI logo
The default Windows icon that was used to represent WASDK is now replaced with a dedicated Windows App SDK logo. The old WinUI logo has been updated to the latest version.

Updates to project and item template titles and descriptions

• Replacing Windows UI Library (WinUI 3) with WinUI 3, as this is the product naming we are using across our docs and communication.
• Following the WPF / UWP template naming conventions starting with the framework name and then the project title. E.g. Blank App, Packaged (WinUI 3 in Desktop) => WinUI Blank App (Packaged)
• Changing Custom Control to Templated Control, which is the correct name for this item template.
• Making descriptions less verbose.

Updates to project and item template icons
Instead of using the default WinUI logo for every template, we are now using individual icons following the Visual Studio design guidelines for iconography (and similar to what WPF and UWP have been using). This helps the developer to understand what the template is about and what language it's using.

Mock-up: original vs. new

Mock-up: original vs. new

[Lamparter]

"WinUI Blank App" isn't quite grammatically correct as it isn't the correct order of words. It should be "Blank WinUI App" to maintain readability and conciseness - [adj., (noun)] (Blank WinUI App) is the correct word order rather than the proposed pattern [noun, adj., noun] (WinUI Blank App)