Implement list comprehension and list aggregation

Fixes #910 and #909

let average = 
  reduce z, a in ages from 0 {
    yield z + a;
  };

let ages = 
  for p in people {
    yield p.age;
  };

[x] RibByteCodeCursor for Jump loops
[x] Math operations
[x] Type inference parts of all of the above. As reviewers may see, it's consistent with the existing approach for rest of the expressions which validates the approach.
[x] Remove Clone from interpreter stack values (a derived outcome, yet a good outcome)
[x] Remove duplicate types between golem-rib and golem-worker-service-base (Ex: RibInputValue). Now we have only 1 single type which is RibInput across the project which acts as the global inputs to a rib script
[x] Make rib_interpreter module , stack values etc private to golem_rib, and only expose RibInput (which is just a wrapper over HashMap of global inputs) to other modules. i.e, golem-worker-service has lesser visibility to golem-rib details with this PR.
[x] Other needed clean ups

golemcloud / golem