[cDAC] Implement CheckContext for cDAC

[barosiak]

Summary

Implements CheckContext in the managed cDAC. Removes the UNSUPPORTED_DbgSkipStackCheck config bypass from the native DAC.

Changes

• Added ContextControlFlags property to the platform context interface hierarchy
• Removed DbgSkipStackCheck config knob, dead globals, and skip logic from native DAC

Tests

• SP in-range, out-of-range, and at-boundary validation across all 6 target architectures
• No-control-flag early exit with verification that stack data is never queried

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[Copilot]

Pull request overview

This PR wires up DacDbiImpl.CheckContext in the managed cDAC implementation by parsing the incoming platform context buffer and (when control flags are present) validating the stack pointer against the thread’s cached stack bounds. On the native DAC side, it removes the UNSUPPORTED_DbgSkipStackCheck opt-out and related globals.

Changes:

• Implement DacDbiImpl.CheckContext in managed code with stack-pointer range validation gated on context control flags.
• Extend the platform context abstractions to expose ContextControlFlags for architecture-specific masking.
• Add targeted unit tests for CheckContext and remove skip-stack-check knob/logic from the native DAC implementation.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/native/managed/cdac/tests/DacDbiImplTests.cs	Adds unit tests covering CheckContext behavior for control-flag vs no-control-flag scenarios across target-arch strings.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs	Implements managed CheckContext logic (reads context bytes, conditionally validates SP range, returns HRESULTs).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/IPlatformContext.cs	Adds ContextControlFlags to the public platform context interface.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/IPlatformAgnosticContext.cs	Adds ContextControlFlags to the public platform-agnostic context interface.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/ContextHolder.cs	Plumbs ContextControlFlags through the ContextHolder<T> wrapper.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/AMD64Context.cs	Provides architecture-specific ContextControlFlags value for AMD64 contexts.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/ARMContext.cs	Provides architecture-specific ContextControlFlags value for ARM contexts.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/ARM64Context.cs	Provides architecture-specific ContextControlFlags value for ARM64 contexts.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/LoongArch64Context.cs	Provides architecture-specific ContextControlFlags value for LoongArch64 contexts.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/RISCV64Context.cs	Provides architecture-specific ContextControlFlags value for RISC-V64 contexts.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/X86Context.cs	Provides architecture-specific ContextControlFlags value for x86 contexts (public type).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/CorDbHResults.cs	Adds CORDBG_E_NON_MATCHING_CONTEXT constant for managed HRESULT parity.
src/coreclr/debug/daccess/dacdbiimplstackwalk.cpp	Removes UNSUPPORTED_DbgSkipStackCheck-based bypass and dead globals; always enforces stack-range check when control flags are present.