Heartbeat rules action does not unwrap variables from entities

I have a rule that results in logging a heartbeat activity. One of the variables comes from an entity. Rules automatically wraps the variable in an EntityValueWrapper and this makes its way to rules_action_heartbeat_activity_log(), which does not properly unwrap the EntityValueWrapper. This leads to activity messages such as "Property name liked Property name".

This sounds related to #1522100: Flags property not showing properly

I expect this is a problem for any variables based on custom entities.

I think the solution involves checking whether each variable is an EntityValueWrapper and, if it is, unwrapping it.