Document new ExceptionHandlerOptions.SuppressDiagnosticsCallback setting

[Copilot]

Fixes #36057
Fixes #35852

This PR documents the new SuppressDiagnosticsCallback setting introduced in .NET 10 as part of the exception handler middleware improvements.

Changes Made

Enhanced IExceptionHandler Documentation

• Added explanation that IExceptionHandler contains a single method (TryHandleAsync)
• Documented how the exception handling middleware works by iterating through registered handlers
• Clarified the behavior when exceptions are handled vs. unhandled

Documented .NET 10 Breaking Change

• Explained that .NET 10 now suppresses diagnostics (logs and metrics) for handled exceptions by default
• Noted the difference from .NET 8 and 9 behavior where diagnostics were always emitted
• Added context about why this change was made based on user feedback

Added New Configuration Section

Created a dedicated "SuppressDiagnosticsCallback" section with practical code examples:

Revert to .NET 8/9 behavior:

app.UseExceptionHandler(new ExceptionHandlerOptions
{
    SuppressDiagnosticsCallback = context => false
});

Conditional suppression based on exception type:

app.UseExceptionHandler(new ExceptionHandlerOptions
{
    SuppressDiagnosticsCallback = context => context.Exception is ArgumentException
});

Added Documentation Links

• Ensured the breaking change announcement link is accessible in Additional resources

Updated Metadata

• Added ai-usage: ai-assisted metadata as required
• Updated ms.date to current date

Review Feedback Addressed

• Changed "The built-in implementation" to "Exception handling middleware" for clarity
• Removed redundant xref link from Additional resources

The documentation now provides developers with clear guidance on how to configure exception diagnostics behavior in .NET 10 while maintaining backward compatibility options.

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[tdykstra]

@copilot This looks really good! I just left a couple suggestions, which I'd like to resolve before asking others to review.

[wadepickett]

@tdykstra, Looks good, approved, assuming the change you suggested is committed.

[JamesNK]

@copilot

The built-in implementation works by iterating through the registered exception handlers

The built-in implementation of what? I don't think this is clear.

I think it should be rephrased to something like:

Exception handling middleware interates through registered exception handlers...

[Copilot]

Updated to clarify that it's the exception handling middleware that iterates through registered exception handlers. See commit 2c8a4e5.

[JamesNK]

One thing that I commented above. Otherwise it looks good.