[StaticWebAssets] Detects pre-compressed assets (#44976)

[javiercn]

Detects assets that have been pre-compressed by an external tool to avoid conflicts when we compress our own assets, and they end up on the same path as the existing pre-compressed assets.

Forward port of #44976

[Copilot]

Copilot reviewed 6 out of 9 changed files in this pull request and generated 2 comments.

Files not reviewed (3)

• src/StaticWebAssetsSdk/Targets/Microsoft.NET.Sdk.StaticWebAssets.Compression.targets: Language not supported
• test/Microsoft.NET.Sdk.Razor.Tests/StaticWebAssetsBaselines/Build_Detects_PrecompressedAssets.Build.files.json: Language not supported
• test/Microsoft.NET.Sdk.Razor.Tests/StaticWebAssetsBaselines/PublishWorks_With_PrecompressedAssets.Build.files.json: Language not supported

Comments suppressed due to low confidence (2)

test/Microsoft.NET.Sdk.Razor.Tests/StaticWebAssets/DiscoverPrecompressedAssetsTest.cs:93

• [nitpick] The placeholder in the RelativePath metadata should be updated to reflect the actual fingerprint value used in the test.

asset.GetMetadata("RelativePath").Should().Be("js/site#[.{fingerprint=uncompressed}]?.js.gz");

src/StaticWebAssetsSdk/Tasks/Compression/DiscoverPrecompressedAssets.cs:95

• The conditional check should first check for '.br' before '.gz' to ensure correct assignment of 'fileExtension' and 'assetTraitValue'.

if (!asset.RelativePath.EndsWith(".gz", StringComparison.OrdinalIgnoreCase))