Refactor FieldData accumulators in DI to CallbackAccumulator<FieldData>

[Copilot]

No description provided.

[dotnet-policy-service]

Tagging subscribers to this area: @steveisok, @tommcdon, @dotnet/dotnet-diag
See info in area-owners.md if you want to be subscribed.

[Copilot]

Pull request overview

The PR description frames this as a small follow-up cleanup ("refactor two file-local FieldDataAccumulator helpers to use the existing generic CallbackAccumulator<FieldData> and revert an unnecessary DAC/DBI protocol counter bump"), but the actual diff is a much larger change that also lands the DacDbi FieldData callback-based protocol, the new cDAC IEditAndContinue contract, and supporting data descriptors.

Changes:

• Replace IDacDbiInterface::GetClassInfo / GetInstantiationFieldInfo with callback-based EnumerateClassFields / EnumerateInstantiationFields (managed + native) and refactor rsclass.cpp / rstype.cpp to drive them via CallbackAccumulator<FieldData>; widen FieldData::m_fldInstanceOffset to ULONG64 and m_pFldStaticAddress to CORDB_ADDRESS.
• Add a new cDAC IEditAndContinue contract (EnumerateAddedFieldDescs), new EnCEEClassData / EnCAddedFieldElement / UnorderedArrayBase Data classes + descriptors, Module.EnCClassList (optional FieldAddress), and supporting source-generator changes for nullable FieldAddress.
• Expose GetNumInstanceFieldBytes / IsFieldDescRVA / IsFieldDescEnCNew on IRuntimeTypeSystem, add EEClass.BaseSizePadding, extract CUnorderedArrayBase so cDAC can read it, and add mocks + xUnit tests for the new EnC contract.

Show a summary per file

File	Description
src/coreclr/inc/dacdbi.idl	Replace GetClassInfo/GetInstantiationFieldInfo with Enumerate* callback-based variants; drop DacDbiArrayList_FieldData/ClassInfo decls.
src/coreclr/debug/inc/dacdbiinterface.h	New FP_FIELDDATA_CALLBACK typedef and EnumerateClassFields / EnumerateInstantiationFields virtuals; updated docs.
src/coreclr/debug/inc/dacdbistructures.h	Widen m_fldInstanceOffset to ULONG64 and m_pFldStaticAddress to CORDB_ADDRESS; update setter signatures.
src/coreclr/debug/inc/dacdbistructures.inl	Adjust FieldData inline accessors to match new CORDB_ADDRESS/ULONG64 types.
src/coreclr/debug/daccess/dacdbiimpl.h	Replace GetClassInfo/GetInstantiationFieldInfo decls; change CollectFields to callback form; drop GetTotalFieldCount/InitClassData.
src/coreclr/debug/daccess/dacdbiimpl.cpp	Implement callback-based Enumerate*; update ComputeFieldData to use CORDB_ADDRESS; remove preallocation/count logic.
src/coreclr/debug/di/rsclass.cpp	Drive EnumerateClassFields via CallbackAccumulator<FieldData> and Init the field list from acc.items.
src/coreclr/debug/di/rstype.cpp	Same refactor for EnumerateInstantiationFields.
src/coreclr/inc/utilcode.h	Extract CUnorderedArrayBase (count + TADDR table) from CUnorderedArrayWithAllocator and add cdac_data shim.
src/coreclr/vm/encee.h	Add cdac_data for EnCEEClassData and EnCAddedFieldElement.
src/coreclr/vm/ceeload.h	Add cdac_data<Module>::EnCClassList under FEATURE_METADATA_UPDATER.
src/coreclr/vm/class.h	Add cdac_data<EEClass>::BaseSizePadding.
src/coreclr/vm/datadescriptor/datadescriptor.inc	Add UnorderedArrayBase, EnCEEClassData, EnCAddedFieldElement descriptors; EEClass.BaseSizePadding; FieldOffsetNewEnc global; EditAndContinue contract entry.
.../Abstractions/Contracts/IEditAndContinue.cs	New contract interface (EnumerateAddedFieldDescs) and empty struct.
.../Abstractions/Contracts/IRuntimeTypeSystem.cs	Add GetNumInstanceFieldBytes, IsFieldDescRVA, IsFieldDescEnCNew; make fieldDef nullable on GetFieldDescOffset.
.../Abstractions/ContractRegistry.cs	Expose EditAndContinue accessor.
.../Contracts/CoreCLRContracts.cs	Register EditAndContinue v1.
.../Contracts/Contracts/EditAndContinue_1.cs	New v1 implementation enumerating EnC-added FieldDescs.
.../Contracts/Contracts/RuntimeTypeSystem_1.cs	Implement GetNumInstanceFieldBytes/IsFieldDescEnCNew; promote IsFieldDescRVA to interface; null-handle big-RVA fieldDef.
.../Contracts/Data/{Module,EEClass,EnCEEClassData,EnCAddedFieldElement,UnorderedArrayBase}.cs	New Data classes / fields backing the EnC descriptors.
.../Contracts/DataType.cs / Constants.cs	New DataType values and FieldOffsetNewEnc global.
.../DataGenerator/Parser.cs, Emitter.cs	Source-gen support for optional/nullable [FieldAddress] properties.
.../Legacy/Dbi/{IDacDbiInterface.cs,DacDbiImpl.cs}	Define FieldData struct; implement new managed Enumerate* with optional debug-only legacy validation.
src/native/managed/cdac/tests/...	New mock infrastructure (MockDescriptors.EditAndContinue.cs), EnC contract xUnit tests, and TestOptionalFieldAddr data-generator tests.
docs/design/datacontracts/{EditAndContinue,RuntimeTypeSystem}.md	Document the new contract and the new IRuntimeTypeSystem APIs/globals.

Copilot's findings

• Files reviewed: 36/36 changed files
• Comments generated: 1