Replace `ActivityExtensions.SetStatus` by `Activity.SetStatus(.WithDescription)`

[Kielek]

Where something was calling ActivityExtensions.SetStatus I suppressed warning instead of updating to use Activity.Status \ Activity.StatusDescription. The reason for that is they don't do the same things. In order for Activity.Status \ Activity.StatusDescription to work, users need to also upgrade to a compatible exporter which understands the status fields on Activity. I decided calling the old extension for now was the safer bet.

Originally posted by @CodeBlanch in #2317 (comment)