v14: Async Value Converters

[mattbrailsford]

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

v14

Bug summary

The current value converters implementation is synchronous only and so doesn't allow executing async code when converting property values to strongly typed models.

Specifics

In Umbraco Commerce v15 our who API has been made async and so we need to be able to execute our async services when converting our property value models.

Steps to reproduce

n/a

Expected result / actual result

I expect to be able to execute async code in value converters