Add skeleton project for task-sdk

[kaxil]

closes#42856 | Part of AIP-72 - Task Execution Interface and SDK

This PR adds a skeleton project for AIP-72 Task SDK

It creates this new project, integrates them to breeze & runs it on CI.

The code & tests are just placeholders at this point, we will start adding things needs for DAG Authors in separate PRs.

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[rawwar]

@kaxil , This change is causing mypy pre-commit check to fail with following error:

task_sdk/tests/conftest.py:26: error: Incompatible types in assignment
(expression has type "tuple[()]", target has type "Union[str, list[str]]") [assignment]
config.inicfg["airflow_deprecations_ignore"] = ()

Should the value be an empty string?

Or, I see in other places, we use # type: ignore[assignment,operator] comment.

Edit: Raised this PR to fix: #42976

[potiuk]

Nice!