Make pipeline work with parallel runs

[stellasia]

Description

Initial issue

The component's results were saved using the component name as key, and the component status were saved in the component directly, which makes the following not behaving as expected (and returning the same result for both 'runs'):

    pipe = Pipeline()
    pipe.add_component(ComponentAdd(), "add")
    run_params = [[1, 20], [10, 2]]
    runs = []
    for a, b in run_params:
        runs.append(pipe.run({"add": {"number1": a, "number2": b}}))
    results = await asyncio.gather(*runs)
    print(result)

(note: this code has been turned into a unit test)

What's in this PR?

• This PR introduces a run_id (uuid) in the Orchestrator and this run ID is used to build the key to access the components' status and results.

• By doing so, it appeared that the callback was not needed anymore and was removed, all the processing now happen in the Orchestrator.run_task method that can call its own on_task_complete method without need for partial and protocol and such.

• In order to make the intermediate results still available after a run is done, this PR introduces the ResultStore, that's able to find the results for a given run ID and a given component. Only InMemoryStore implemented so far. Pipeline.run method also return the run_id in a new PipelineResult object (breaking change).

• Not mandatory but possible follow-up PR, that moves the status to the store instead of having them hanging in the Task.

Type of Change

• New feature
• Bug fix
• Breaking change
• Documentation update
• Project configuration change

Complexity

Note

Please provide an estimated complexity of this PR of either Low, Medium or High

Complexity: Medium

How Has This Been Tested?

• Unit tests
• E2E tests
• Manual tests

Checklist

The following requirements should have been met (depending on the changes in the branch):

• Documentation has been updated
• Unit tests have been updated
• E2E tests have been updated
• Examples have been updated
• New files have copyright header
• CLA (https://neo4j.com/developer/cla/) has been signed
• CHANGELOG.md updated if appropriate

[willtai]

Is it possible to use list[str] here?

[stellasia]

It doesn't work with python 3.8 when we do the introspection to find the expected inputs.

[willtai]

LGTM 🏔️