Add Exception Stacks view when viewing a .nettrace with exceptions

[Copilot]

When collecting a trace using dotnet-trace collect, the generated .nettrace file contains call stacks for any exceptions thrown. Previously, while users could see exception events in the Events view and find associated stacks in the Any Stacks view by time filtering, there was no dedicated Exception Stacks view like the one available for .etl files.

This PR adds Exception Stacks view support for .nettrace files by porting the logic from the ETL implementation to the EventPipe implementation.

Changes Made

1. Exception Event Detection: Added detection for "Exception/Start" events in EventPipePerfViewData.OpenImpl() to set the hasExceptions flag
2. UI Integration: Added "Exceptions" stack source to the Advanced Group when exceptions are detected in the trace
3. Stack Source Implementation: Implemented the "Exceptions" case in EventPipePerfViewData.OpenStackSourceImpl() that:
   • Creates a MutableTraceEventStackSource with managed-only stacks
   • Listens for ExceptionStart events
   • Creates stack samples with format "Throw(ExceptionType) ExceptionMessage"
   • Preserves the original call stack from the exception event data

Implementation Details

The implementation follows the exact same pattern as the existing ETL exception handling to ensure consistency:

eventSource.Clr.ExceptionStart += delegate (ExceptionTraceData data)
{
    sample.Metric = 1;
    sample.TimeRelativeMSec = data.TimeStampRelativeMSec;

    // Create a call stack that ends with the 'throw'
    var nodeName = "Throw(" + data.ExceptionType + ") " + data.ExceptionMessage;
    var nodeIndex = stackSource.Interner.FrameIntern(nodeName);
    sample.StackIndex = stackSource.Interner.CallStackIntern(nodeIndex, stackSource.GetCallStack(data.CallStackIndex(), data));
    stackSource.AddSample(sample);
};

Users will now see the "Exceptions" stack source in the Advanced Group when opening .nettrace files that contain exception events, providing the same exception analysis capabilities available for .etl files.

Fixes #1797.

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[brianrob]

Suggested change

	stackSource.OnlyManagedCodeStacks = true;
	stackSource.OnlyManagedCodeStacks = !hasUniversalSystem;

[Copilot]

Updated the setting to use !hasUniversalSystem to include native stacks when available, matching the ETL implementation behavior. Change implemented in commit 33fe190.

[brianrob]

Suggested change

	stackSource.OnlyManagedCodeStacks = !hasUniversalSystem;
	stackSource.OnlyManagedCodeStacks = !m_supportsProcesses;

[Copilot]

Updated to use !m_supportsProcesses which provides a more comprehensive check that includes both system and CPU events, better aligning with the logic for determining stack information availability. Change implemented in commit 2604ed6.

[brianrob]

Copilot Post-Mortem:

• Copilot did quite well with this issue out the gate - it was able to understand the pattern of how to add a stack view without any coaching.
• In the future, I'd love to be able to have copilot test the feature and show me screenshots, but I realize that's likely a ways off.

[marklio]

Looks reasonable

[mconnew]