[DAC] Change EnumMethodInstancesByAddress behavior

[max-charlamb]

Modifies EnumMethodInstancesByAddress to only return a single IXCLRDataMethodInstance representing the instance at the given IP address.

Running diagnostics tests on new behavior

[max-charlamb]

/azp run runtime-diagnostics

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Azure Pipelines could not run because the pipeline triggers exclude this branch/path.

[Copilot]

Pull Request Overview

This PR modifies the EnumMethodInstancesByAddress behavior to return only a single IXCLRDataMethodInstance representing the method instance at the given IP address, rather than enumerating through multiple instances.

Key changes:

• Simplified enumeration logic to return at most one method instance
• Moved native code check from iterator to the start enumeration function
• Replaced iterator-based approach with a single completion flag

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/coreclr/debug/daccess/task.cpp	Simplified EnumMethodInstances::Next() to return single instance and moved native code validation to StartEnumMethodInstancesByAddress()
src/coreclr/debug/daccess/dacimpl.h	Replaced iterator fields with simple completion flag in EnumMethodInstances class
src/coreclr/debug/daccess/daccess.cpp	Added native code check in StartEnumMethodInstancesByAddress() before starting enumeration

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