[Core Feature] [flytekit] Run dispatch_execute and trigger type engine during local task execution

[wild-endeavor]

Motivation: Why do you think this is important?

Generally we made an effort during the development of flytekit to make the local testing experience as similar to what happens in a real backend run as possible. This was not done in one case - local task execution.

In local task execution, it was originally thought to be a feature that when an @task decorated function was run, say inside a unit test, flytekit steps completely out of the way and the raw function is just run.

More and more, this seems like a mistake.

1. This makes unit test behavior differ potentially. When a task is run in a unit test today, we just run the function. But if you wrap the task into a workflow that does nothing except call the task, then flytekit does not step out of the way: the type engine is triggered and inputs and outputs are translated between Python and Flyte literal types.
2. Types that rely on the TypeEngine getting invoked (like FlyteFile, FlyteDirectory, and FlyteSchema) behave differently given 1.
3. There doesn't seem to be good reason to diverge from mantra of maintain as much similarity as possible between unit testing and live production run.

Goal: What should the final outcome look like, ideally?

The behavior for running a task locally by itself and running a task locally inside a workflow should be the same.