[test] SRE ILGenerator test for methodref and fieldref token caching

[test] SRE ILGenerator test for methodref and fieldref token caching

Regression test for https://bugzilla.xamarin.com/show_bug.cgi?id=59364

We need to cause SRE to generate the same methodref/fieldref token from two
different reflection objects.  That happens if you get the same method or field
via a base and a derived class so that the MemberInfo:DeclaredType is different
but the underlying MonoMethod* or MonoClassField* is the same.