* [Concurrency] Adjust task escalation APIs to SE accepted shapes
* adjust test a little bit
* Fix closure lifetime in withTaskPriorityEscalationHandler
* avoid bringing workaround func into abi by marking AEIC
Previously these records were not used at all, so changing this has no
impact on existing runtimes. Note that we changedd the FunctionType
because the previous one was slightly incorrect -- the context comes
LAST in the type, not first.
