We should be checking that the PDB version matches the DLL when we find the .pdb file next to the .dll.

The easiest way to handle both cases (including the embedded PBD) is to use PEReader.TryOpenAssociatedPortablePdb method: https://source.dot.net/#System.Reflection.Metadata/System/Reflection/PortableExecutable/PEReader.cs,d04ae6c22fdcad8f,references

Originally posted by @tmat in #57073 (comment)