Add experimental attribute and suppress warnings

[mitchdenny]

Introduce an experimental attribute for publisher methods and disable related warnings in playground and tests to streamline development and evaluation.

Fixes: #8304

[Copilot]

Pull Request Overview

This pull request introduces a new experimental attribute ("ASPIREPUBLISHERS001") for publisher methods and updates the warning suppression across tests and playground applications to streamline development and evaluation.

• Replaces the old experimental identifier in Azure publisher extensions with the new "ASPIREPUBLISHERS001".
• Adds the experimental attribute to publisher extension methods in multiple projects.
• Updates test and playground files to disable the new warning and removes now-unneeded suppressions for the deprecated identifier.

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/Aspire.Hosting.Tests/Backchannel/AppHostBackchannelTests.cs	Disables the new experimental warning for test evaluations.
tests/Aspire.Hosting.Docker.Tests/DockerComposePublisherTests.cs	Suppresses experimental warnings for Docker publisher tests.
src/Aspire.Hosting/PublisherDistributedApplicationBuilderExtensions.cs	Applies the experimental attribute to the generic AddPublisher method.
src/Aspire.Hosting.Kubernetes/KubernetesPublisherExtensions.cs	Applies the experimental attribute to both Kubernetes publisher overloads.
src/Aspire.Hosting.Docker/DockerComposePublisherExtensions.cs	Applies the experimental attribute to both Docker Compose publisher overloads.
src/Aspire.Hosting.Azure/AzurePublisherExtensions.cs	Updates the experimental attribute from the old ASPIREAZURE001 to ASPIREPUBLISHERS001.
playground/publishers/Publishers.AppHost/Program.cs	Adds warning suppression for the new identifier and removes deprecated suppression for Azure.

Comments suppressed due to low confidence (2)

playground/publishers/Publishers.AppHost/Program.cs:17

• The removal of warning suppression for ASPIREAZURE001 indicates that AzurePublisher warnings are now expected to be handled by the new experimental attribute; please confirm that this change is intended and update related documentation if necessary.

builder.AddAzurePublisher("azure");

src/Aspire.Hosting.Azure/AzurePublisherExtensions.cs:19

• [nitpick] Ensure that the experimental attribute identifier 'ASPIREPUBLISHERS001' is consistently documented and used throughout the codebase to avoid confusion with the previous identifier.

[Experimental("ASPIREPUBLISHERS001", UrlFormat = "https://aka.ms/dotnet/aspire/diagnostics#{0}")]

[davidfowl]

We don’t need it for compose as that’s prerelease