Sample for `IDynamicInterfaceCastable` (dotnet#3744)

* Add sample for IDynamicInterfaceCastable

* Apply suggestions from code review

Co-authored-by: Youssef Victor <31348972+Youssef1313@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: David Pine <david.pine@microsoft.com>

* Update delegate names

* Fix naming of private members

Co-authored-by: David Pine <david.pine@microsoft.com>

* Explicitly set UseAppHost=true

* Add metadata to readme

* Make sample find MSVC compiler

* Update link to API doc

* Apply suggestions from code review

Co-authored-by: Youssef Victor <31348972+Youssef1313@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: Youssef Victor <31348972+Youssef1313@users.noreply.github.com>

Co-authored-by: Youssef Victor <31348972+Youssef1313@users.noreply.github.com>
Co-authored-by: David Pine <david.pine@microsoft.com>

Update README.md (dotnet#3743)

Bump Microsoft.AspNetCore.Mvc.NewtonsoftJson from 3.1.5 to 3.1.6 in /…

…core/diagnostics/DiagnosticScenarios (dotnet#3732)

* Bump Microsoft.AspNetCore.Mvc.NewtonsoftJson

Bumps [Microsoft.AspNetCore.Mvc.NewtonsoftJson](https://github.com/aspnet/AspNetCore) from 3.1.5 to 3.1.6.
- [Release notes](https://github.com/aspnet/AspNetCore/releases)
- [Changelog](https://github.com/dotnet/aspnetcore/blob/master/docs/CrossRepoBreakingChanges.md)
- [Commits](dotnet/aspnetcore@v3.1.5...v3.1.6)

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* Update to 3.1 LTS

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Bill Wagner <wiwagn@microsoft.com>

Bump NUnit3TestAdapter in /csharp/unit-testing/NUnit.TestProject (dot…

…net#3730)

Bumps [NUnit3TestAdapter](https://github.com/nunit/nunit3-vs-adapter) from 3.16.1 to 3.17.0.
- [Release notes](https://github.com/nunit/nunit3-vs-adapter/releases)
- [Commits](nunit/nunit3-vs-adapter@V3.16.1...V3.17)

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Merge pull request dotnet#3702 from RussKie/Add_WindowsForms_TaskDial…

…og_demo

Add Windows Forms TaskDialog API sample

Merge pull request dotnet#3702 from RussKie/Add_WindowsForms_TaskDial…

…og_demo

Add Windows Forms TaskDialog API sample

Merge pull request dotnet#3697 from dotnet/azure-sdk-landing-page

Sample app for track 2 Azure SDKs

Merge pull request dotnet#3679 from IEvangelist/unit-testing-coverage

Unit testing code coverage

Merge pull request dotnet#3679 from IEvangelist/unit-testing-coverage

Unit testing code coverage

Bump Microsoft.AspNetCore.Mvc.NewtonsoftJson (dotnet#3674)

Bumps [Microsoft.AspNetCore.Mvc.NewtonsoftJson](https://github.com/aspnet/AspNetCore) from 3.1.4 to 3.1.5.
- [Release notes](https://github.com/aspnet/AspNetCore/releases)
- [Changelog](https://github.com/dotnet/aspnetcore/blob/master/docs/CrossRepoBreakingChanges.md)
- [Commits](https://github.com/aspnet/AspNetCore/commits)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>