Runtime-async continuation object reading with Cordb

[rcj1]

This PR ensures that we are able to access continuation objects through APIs such as CordbObjectValue::GetFieldValue. As the dynamically generated continuation types with the local variable fields do not have metadata, we use the parent class which does have metadata. We will therefore not be able to view the locals fields through these APIs, but with the low likelihood that someone is digging this deep into implementation details, this should be an acceptable trade-off.

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[Copilot]

Pull Request Overview

This PR adds special handling for continuation types in the debugger to map them to their base continuation class type for debugging purposes. The variable name "IfSubTypeCreated" suggests this is a lazily-initialized global that may be NULL before any continuation subtypes are created.

• Adds checks for continuation types using IsContinuation() in debugger type conversion functions
• Replaces continuation subtypes with the base continuation class type (g_pContinuationClassIfSubTypeCreated) for debugger type information
• Applies this pattern consistently across both EE debugger and DAC debugger interface implementations

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
src/coreclr/debug/ee/debugger.cpp	Adds continuation type handling in TypeHandleToBasicTypeInfo and TypeHandleToExpandedTypeInfo to replace continuation types with base class
src/coreclr/debug/daccess/dacdbiimpl.cpp	Adds continuation type handling in GetClassTypeInfo and TypeHandleToBasicTypeInfo (DAC version) with same replacement pattern

[thaystg]

LGTM

[rcj1]

/ba-g unrelated fails