Missing ability to remove/unset person properties #111
Description
IPostHogClient.IdentifyAsync(...) accepts the parameters personPropertiesToSet and personPropertiesToSetOnce, mapped to event properties $set and $set_once, respectively. As far as I can tell, however, the ability to remove person properties by means of the $unset property is not surfaced anywhere in the library.
As a workaround, one can of course capture an $identify event manually, with the aforementioned $unset property, but it would be nice if this mechanism was available in e.g. an IdentifyAsync overload.