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?

• Added basic unit tests

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• 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]

❌ Build CefSharp 130.1.90-CI5096 failed (commit ae53ed4b50 by @amaitland)

[amaitland]

I was hoping to have this done for M131, feels a bit too rushed, so will wait for M132

[amaitland]

Need to manually cherry pick changes from PR cefsharp/CefSharp.Wpf.HwndHost#31

[AppVeyorBot]

❌ Build CefSharp 131.2.70-CI5106 failed (commit dd051548c7 by @amaitland)

[AppVeyorBot]

✅ Build CefSharp 131.2.70-CI5116 completed (commit f97afa386e by @amaitland)

[AppVeyorBot]

✅ Build CefSharp 131.2.70-CI5118 completed (commit 02f8d697b6 by @amaitland)

[AppVeyorBot]

✅ Build CefSharp 131.3.10-CI5122 completed (commit 440a946ebe by @amaitland)

[AppVeyorBot]

❌ Build CefSharp 131.3.10-CI5124 failed (commit d8816e3d63 by @amaitland)

[amaitland]

I might merge this without rewriting the example project in the short term. There's a few ways to do it and I'm just not sure which one makes the most sense. Needs to be easy to follow, largely self contained for external users who want to use as a base for their application.

[AppVeyorBot]

✅ Build CefSharp 131.3.10-CI5143 completed (commit 4e983ca0a9 by @amaitland)

[amaitland]

Going to merge this now, there are likely some tweaks required to the Nuget pacakges, they'll be addressed after this is merged (once we have a nuget CI set of packages, can test the packages with the minimal example)