[Blazor] Add vary header to uncompressed endpoints

[javiercn]

All the endpoints for a given route with multiple representations must have Vary applied to it.

[dotnet-policy-service]

Thanks for your PR, @@javiercn.
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[Copilot]

Pull Request Overview

This PR adds a "Vary: Accept-Encoding" header to uncompressed static asset endpoints in Blazor WebAssembly applications. The change helps prevent caching issues where browsers might cache an uncompressed response and serve it even when compression is requested, improving HTTP caching behavior.

• Updates static web asset endpoint configurations to include the Vary header
• Applies to all uncompressed static assets like .dll, .js, .wasm, and other framework files
• Changes are reflected in test baseline files to match the new behavior

Reviewed Changes

Copilot reviewed 13 out of 72 changed files in this pull request and generated no comments.

File	Description
StaticWebAssets_PublishMinimal_Works.Publish.staticwebassets.json	Updated baseline showing Vary header added to all uncompressed endpoints
StaticWebAssets_HostedApp_ReferencingNetStandardLibrary_Works.Build.staticwebassets.json	Updated baseline showing Vary header added to all uncompressed endpoints
StaticWebAssets_Build_Hosted_Works.Build.staticwebassets.json	Updated baseline showing Vary header added to all uncompressed endpoints

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