Import CefSharp.Wpf.HwndHost into main repository.

[amaitland]

Fixes: [issue-number]

4982

Summary:

• Import the CefSharp.Wpf.HwndHost code into a subfolder in the CefSharp.Wpf project

Changes:

• Import code into HwndHost folder (namespace in CefSharp.Wpf project)
• Add new common interface
• Add the existing example (though will be migrated to MinimalExample shortly)

How Has This Been Tested?

• Manual currently (We can add a test into the Test project)

Screenshots (if appropriate):

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [x] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Updated documentation

Checklist:

• [ ] Tested the code(if applicable)
• [ ] Commented my code
• [ ] Changed the documentation(if applicable)
• [ ] New files have a license disclaimer
• [ ] The formatting is consistent with the project (project supports .editorconfig)

[amaitland]

Still a few thing to resolve

• [ ] Meta nuget package
• [ ] Add some tests now the project is in the main repo
• [ ] Update the example to be part of the Wpf example so it can used the existing tabbed interface
• [ ] Remove the current Example.

[AppVeyorBot]

:x: Build CefSharp 130.1.90-CI5096 failed (commit https://github.com/cefsharp/CefSharp/commit/ae53ed4b50 by @amaitland)