[clr-interp] Add initial CoreCLR interpreter func-eval support

[matouskozak]

Description

This adds initial func-eval support for threads stopped in CoreCLR interpreter code.

• execute pending evals from the interpreter breakpoint path after the debugger callback returns
• queue interpreter func-eval requests on the interpreter thread context instead of using native-context hijacking
• skip native-only setup for interpreter evals, including executable breakpoint segment allocation, SP alignment validation, and register/context updates that rely on real native frames
• reuse the direct completion path for interpreter evals, where completion is signaled without the native breakpoint trap mechanism

Testing:

• Locally on iOS simulator
• DiagnosticTest TBD

Future Work

• Func evaluation on exceptions

---

#125959

[Copilot]

Pull request overview

Adds initial debugger func-eval support when the target thread is stopped in CoreCLR interpreter code, by avoiding native-context hijacking and instead running queued evals from the interpreter breakpoint path.

Changes:

• Adds a pending func-eval slot to the interpreter thread context and triggers execution after the breakpoint debugger callback returns.
• Extends DebugInterface/Debugger with an interpreter-specific hook to execute pending evals.
• Adjusts FuncEvalSetup / DebuggerEval initialization to skip native-only setup (e.g., executable breakpoint segment allocation, SP alignment checks) for interpreter evals.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/coreclr/vm/interpexec.h	Adds InterpThreadContext::m_pPendingFuncEval storage for interpreter-thread func-evals.
src/coreclr/vm/interpexec.cpp	Executes pending interpreter func-evals from the INTOP_BREAKPOINT handler using a synthetic filter context.
src/coreclr/vm/dbginterface.h	Adds ExecutePendingInterpreterFuncEval(Thread*) to the debug interface under FEATURE_INTERPRETER.
src/coreclr/debug/ee/debugger.h	Declares the Debugger implementation of ExecutePendingInterpreterFuncEval.
src/coreclr/debug/ee/debugger.cpp	Implements pending-eval execution and updates FuncEvalSetup/DebuggerEval to support interpreter eval flow.

[jkotas]

Can this be done inside InterpBreakpoint?

CONTEXT is a very large structure. We do not want to add it to the main interpreter executor loop native frame. It would likely regress performance of the interpreter executor loop.

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