Support Proc.new(Void*, Void*) in the interpreter

[HertzDevil]

Fixes part of #12495.

This constructor is now a primitive in interpreted code, and accepts both CompiledDef pointers and C function pointers, assuming the latter by default, unless a previous ProcLiteral has created the pointer. The interpreter will then compile a wrapper on the fly; eventually the external_var_get primitive from the original issue may adopt a similar technique.

Two Procs with the same C function pointer will refer to the same CompiledDef. Each CompiledDef more or less maintains its own FFI::CallInterface; there is no FFI closure involved, unlike Crystal procs.

This enables networking on Windows inside the interpreter, and also drops a workaround in the IOCP event loop.