Few interpreter EH fixes

[janvorli]

• Correctly normalize objects that are not derived from Exception class before throwing them from the interpreter
• Ensure managed exceptions from QCALLs invoked by the interpreter are properly handled
• Add null check to INTOP_ZEROBLK_IMM

[Copilot]

Pull Request Overview

This PR implements several exception handling fixes for the interpreter in CoreCLR. The changes ensure proper normalization of thrown objects and improved handling of managed exceptions from native calls.

Key changes:

• Extracts duplicated exception normalization logic into a reusable NormalizeThrownObject function
• Adds proper exception handling for QCALL invocations within the interpreter using PAL_TRY/PAL_EXCEPT
• Adds null pointer validation to the INTOP_ZEROBLK_IMM interpreter operation

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/coreclr/vm/jithelpers.cpp	Refactors IL_Throw to use the new NormalizeThrownObject function, removing duplicate code
src/coreclr/vm/interpexec.cpp	Adds exception handling for unmanaged method transitions, null check for INTOP_ZEROBLK_IMM, and proper normalization for interpreter throws
src/coreclr/vm/exceptionhandling.h	Declares the new NormalizeThrownObject function
src/coreclr/vm/exceptionhandling.cpp	Implements the NormalizeThrownObject function with the extracted logic

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