Temporary fix on patching SDK for System.Security.Cryptography.Pkcs.dll

[heng-liu]

When implementing verification and signing, we bring in System.Security.Cryptography.Pkcs.dll and several dlls for netstandard2.1, which is in extension but not in netcoreapp3.x/5.0.
So we encounter an exception of System.Security.Cryptography.Pkcs.dll not found in patching tests as those dlls are not brought in in SDK.
For now, we need to temporary copy those dlls and update the deps.json files in patching.
For permeate fix, we need to wait for SDK team bring in those dlls.

Should create an SDK issue and point to it.
dotnet/sdk#3629
#8570