Allow programs to call methods from different ecosystems.

I've implemented a custom tactic so that the changes are transparent to the surface language for constructors, methods, destructors and upgrades.

There are some things that need to be improved:

1. Only works if the EcosystemIdEnum : FinEnum EcosystemId is given explicitly and not inferred as an instance. We need to figure out how to properly reduce an expression with instance arguments in it.
2. Multimethods require the user to provide the ecosystem id explicitly in the code. In the future this should be automatized too.