Mark experimental packages

[RussKie]

Resolves #4643
Resolves #4649

If the property isn't specified, the build will fail:

Microsoft Reviewers: Open in CodeFlow

[joperezr]

Left a question but that is unrelated to your changes. This LGTM thanks for fixing @RussKie!

Did you get a chance to validate the consumption side and ensure that an app using this package APIs gets the right diagnostic IDs?

[RussKie]

Did you get a chance to validate the consumption side and ensure that an app using this package APIs gets the right diagnostic IDs?

If you remove any of the new suppressions, you'll see the build failing. For example:

D:\Development\dotnet-extensions\test\Libraries\Microsoft.Extensions.Options.ContextualOptions.Tests\ContextualOptionsFactoryTests.cs(52,25): error EXTEXP0017: 'Microsoft.Extensions.Options.Contextual.ValidateContextualOptions<System.Collections.Generic.List<string>>' is for evaluation purposes o 
nly and is subject to change or removal in future updates. Suppress this diagnostic to proceed. (https://aka.ms/dotnet-extensions-warnings/EXTEXP0017) [D:\Development\dotnet-extensions\test\Libraries\Microsoft.Extensions.Options.ContextualOptions.Tests\Microsoft.Extensions.Options.Contextual.Test 
s.csproj::TargetFramework=net6.0]

[dotnet-comment-bot]

🎉 Good job! The coverage increased 🎉
Update MinCodeCoverage in the project files.

Project	Expected	Actual
Microsoft.Extensions.Telemetry	92	93
Microsoft.AspNetCore.Diagnostics.Middleware	99	100

Full code coverage report: https://dev.azure.com/dnceng-public/public/_build/results?buildId=459079&view=codecoverage-tab