WinFormsDesigner does not copy PDB files into cache folder

### Environment

msvs 17.11.6

### .NET version

net8

### Did this work in a previous version of Visual Studio and/or previous .NET release?

no

### Issue description

When designer copies references into cache folder, it does not copy pdb files. As the result, in case of exception in custom designer related code, there is no debug information (like line, where exception happens).
I know the option when I can embed PDB into DLL, but this is sometimes not the option, say, when DLL is modified by obfuscator (and change PDB as well), or PDB in modified to reroute source into external source server.

### Steps to reproduce

check cache folder and there is no PDB files for copied dlls

### Diagnostics

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