feat(sdk-python): Port in-line expressions to Python SDK

[Snarr]

This PR ports the in-line expression changes to the Python SDK.

[sauljabin]

I have approve it, but before merging check if it is possible to get rid of the dependency at WfRunVariable and use the WorkflowCondition.

The other WfRunVariable parameter are attributes of the class, WorkflowThread would be a dependency that maybe we can avoid, if we can the better

[sauljabin]

1 underscore for internal 2 for language related ones.

example __init__ 2 underscore

[sauljabin]

if the default value is None use = None here

Optional[WorkflowThread]

[sauljabin]

I'm not totally convince if we should do this.

Actually we can do something like:

def is_equal_to(self, rhs: Any) -> WorkflowCondition:
        return WorkflowCondition(self, Comparator.EQUALS, rhs)

Even though we can implement it similar to java, I would prefer to reduce the dependencies in python.

Circular dependencies errors are very common in python. They (python devs) are going to get rid of it, and make it a more java like language, but i do not know when.

[Snarr]

@sauljabin I agree with your proposal, it is unnecessary to depend on the parent condition methods when creating a new WorkflowCondition is so simple. If the code for creating a new WorkflowCondition were more complex, it may make sense to centralize it in one place and rely on this dependency injection or another class to hold the methods.

There is one additional method that may not make sense to port without injecting the parent thread dependency:

    @Override
    public void assignTo(Serializable rhs) {
        parent.mutate(this, VariableMutationType.ASSIGN, rhs);
    }

Without injecting the parent WorkflowThread at the constructor, this method may not make sense or be easy to use. Instead, we would have to pass it to the method as an argument, which would not save the user much code and (in my opinion) be less readable.

[sauljabin]

You are right, I did not see the mutate

[coltmcnealy-lh]

I'm confused. Don't you need to edit the to_variable_assignment() method in order for this to work?