v14: Async Healthchecks

[mattbrailsford]

Which Umbraco version are you using? (Please write the exact version, example: 10.1.0)

v14

Bug summary

The current health checks implementation only supports async when fetching the status, however the execute action behaviour of health checks only supports running synchronously.

Specifics

In Umbraco Commerce v15 our who API has been made async and so we need to be able to execute our async services in response to health check interactions.

Steps to reproduce

n/a

Expected result / actual result

I expect to be able to execute async code in response to a health check interaction

[AndyButland]

Fixed with #17090 and due in 15.3.