fix: Don't rethrow in DisposeComponents directly

[linkdotnet]

DisposeComponents did check immediately for AssertNoUnhandledExceptions which can creates race conditions when DisposeAsync/Dispose throws fast enough (aka in the sync part) but may behave oddly in the async part. Test201 was super flaky due this race condition.

So this "take" consolidates a central way of getting an exception out of the "DisposeComponents" method

[egil]

Horray, great catch!

[Copilot]

Pull Request Overview

This PR fixes a race condition in the DisposeComponents method by removing the immediate exception rethrowing behavior and consolidating exception handling through the Renderer.UnhandledException task. The change addresses flakiness in Test201 by ensuring consistent behavior for both synchronous and asynchronous disposal exceptions.

• Removed immediate AssertNoUnhandledExceptions() call from DisposeComponents method
• Updated test expectations to check exceptions via Renderer.UnhandledException instead of expecting direct throws
• Updated documentation to reflect the new consistent exception handling pattern

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/bunit/Rendering/BunitRenderer.cs	Removed immediate exception assertion to prevent race conditions
tests/bunit.tests/BunitContextTest.cs	Updated test to use new exception handling pattern via Renderer.UnhandledException
docs/site/docs/interaction/dispose-components.md	Updated documentation to explain new consistent exception handling approach
docs/samples/tests/xunit/DisposeComponentsTest.cs	Updated sample code to demonstrate proper exception handling patterns

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