[clr-interp] Add support for synchronized methods

[davidwrighton]

• The general approach is to wrap the method is a try/finally block
  • This is done by appending some IL to the method, and adding an EH clause
  • This required implementing a few abstraction boundaries so that the code/eh clauses could be rewritten within the interpreter
• Synchronized methods also re-use the shadow this pointer logic
• existing IL which is encoded as a RET needs to actually have the semantics of a LEAVE to to the actual return from the method
• We also have a couple of "intrinsic" tokens which the our implementation of CALL now recognizes.

[Copilot]

Pull Request Overview

This PR adds support for synchronized methods in the CLR interpreter by implementing a try/finally pattern to handle monitor enter/exit operations.

Key changes:

• Wraps synchronized methods in try/finally blocks with additional IL opcodes for monitor operations
• Implements shadow this pointer logic for synchronized instance methods
• Converts RET instructions to LEAVE operations in synchronized methods to ensure proper cleanup

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/coreclr/vm/interpexec.cpp	Adds INTOP_CALL_HELPER_V_SA opcode handler and HELPER_FTN_V_PP typedef
src/coreclr/interpreter/intops.h	Defines intrinsic tokens for synchronized method implementation
src/coreclr/interpreter/inc/intops.def	Adds INTOP_CALL_HELPER_V_SA opcode definition
src/coreclr/interpreter/compiler.h	Adds synchronized method state tracking variables and helper methods
src/coreclr/interpreter/compiler.cpp	Implements synchronized method compilation logic, IL rewriting, and monitor operations

[kg]

(Not a complaint about this implementation) Is there a reason we couldn't have the interpreter itself do the synchronization?

[kg]

The complexity bothers me but I assume there's a good reason why it can't be simpler. Other than the comments I left it LGTM