New engine logging

[desertaxle]

Adds logging for run creation and completion to the new engine so that it feels familiar and homey.

Also adds support for logging prints to the new engine.

Also fixes some issues with task run naming.

Example

For this flow:

from prefect import flow, task


@flow(retries=3, log_prints=True)
def my_flow(foo: bool):
    my_other_flow(42)
    print("Hello, world!")
    return slow_task.submit()

@flow
def my_other_flow(bar: int):
    pass

@task(timeout_seconds=10, task_run_name="bloop")
def slow_task():
    print("Sleeping...")
    import time
    time.sleep(1)

if __name__ == "__main__":
    my_flow(foo=True)

Running will produce this output:

22:14:31.434 | INFO    | prefect.engine - Created flow run 'didactic-prawn' for flow 'my-flow'
22:14:31.437 | INFO    | prefect.engine - View at http://127.0.0.1:4200/flow-runs/flow-run/785b8466-010a-4338-8f68-b0e1e10d5649
22:14:32.088 | INFO    | Flow run 'didactic-prawn' - Created subflow run 'burrowing-finch' for flow 'my-other-flow'
22:14:32.090 | INFO    | prefect.engine - View at http://127.0.0.1:4200/flow-runs/flow-run/ae098ba9-e966-43e1-bdf3-910f8ad50b7a
22:14:32.172 | INFO    | Flow run 'burrowing-finch' - Finished in state Completed()
22:14:32.185 | INFO    | Flow run 'didactic-prawn' - Hello, world!
22:14:32.191 | INFO    | Flow run 'didactic-prawn' - Submitting task slow_task to thread pool executor...
22:14:32.209 | INFO    | prefect.engine - Created task run 'slow_task-0' for task 'slow_task'
22:14:32.242 | INFO    | Task run 'bloop' - Sleeping...
22:14:33.267 | INFO    | Task run 'bloop' - Finished in state Completed()
22:14:33.294 | INFO    | Flow run 'didactic-prawn' - Finished in state Completed('All states completed.')

Checklist

• This pull request references any related issue by including "closes <link to issue>"
  • If no issue exists and your change is not a small fix, please create an issue first.
• If this pull request adds new functionality, it includes unit tests that cover the changes
• This pull request includes a label categorizing the change e.g. maintenance, fix, feature, enhancement, docs.

For documentation changes:

• This pull request includes redirect settings in netlify.toml for files that are removed or renamed.

For new functions or classes in the Python SDK:

• This pull request includes helpful docstrings.
• If a new Python file was added, this pull request contains a stub page in the Python SDK docs and an entry in mkdocs.yml navigation.

[cicdw]

Nice, this looks great!