Re-add getAddress() for non-MuxRPC method calls
Problem: Removing all `getAddress()` usage was too aggressive -- it's
still a method that Secret-Stack exposes, and so we should still test
for it, but we should **only test for it over in-process method calls**.
When using MuxRPC, we should always use `address()`.
Solution: Use `getAddress()` when the method isn't being called via
MuxRPC.