Add type wrapper

[rpeden]

This pull request adds a wrapper class that helps this decorator do what it needs to do while still passing the type check that is currently causing it to fail when run in a deployment, as mentioned in https://github.com/PrefectHQ/prefect/issues/7338. The update in this PR makes the decorator usable without requiring changes to Prefect.

Example

@alert_on_failure(block_type=SlackWebhook, block_name="test")
@flow
def test_flow():
    print("testing")

isinstance(test_flow, Flow)
---> returns True

Checklist

• [X] This pull request references any related issue
• [X] This pull request includes tests or only affects documentation.
• [ ] Summarized PR's changes in CHANGELOG.md

[ahuang11]

This is an awesome idea!