!!DO NOT MERGE!! Support reusable slices

[DamianEdwards]

This is WIP, not ready to merge yet. If I do decide to merge this I might mark it experimental initially as it's a bit scary.

Related to #79

Copilot reviewed 5 out of 8 changed files in this pull request and generated no comments.

Files not reviewed (3)

• samples/RazorSlices.Samples.WebApp/Slices/Lorem/LoremFormattable.cshtml: Evaluated as low risk
• tests/BenchmarksWebApps/RazorSlices.Benchmarks.RazorClassLibrary.Local/ReusableHello.cshtml: Evaluated as low risk
• src/RazorSlices/IRazorReusableSlice.cs: Evaluated as low risk

Comments suppressed due to low confidence (2)

tests/BenchmarksWebApps/RazorSlices.Benchmarks.RazorClassLibrary.Local/LocalVersion.cs:19

• The new method RenderReusableHello is introduced without any test coverage. Please add tests to verify its behavior.

public static ValueTask<string> RenderReusableHello()

src/RazorSlices/RazorSlice.cs:204

• Ensure that the new reusable slice functionality, including the commented-out Dispose call, is covered by tests.

//Dispose();