Interpreting foreign functions call information as activity

Feature request

It'll be great if time between:
"HEC YY: stopping thread ZZZZZ (making a foreign call)" and
"HEC YY: running thread ZZZZZ" where YY and ZZZZZ are same between events and intepret as a single foreign call.

Activity diagram to show it as this thread is doing something foreign and this could be shown as separate coloured activity inside HEC graphs for YY execution unit.

This is a time spent somewhere else, but affecting us as we have to wait for it at this thread, so it's kind of activity albeit it is outside Haskell. It's time spent in foreign call which will be useful to be represented and measured.

首先定位对“stopping thread ... (making a foreign call)”的事件处理，以及匹配的“running thread ...”消息。追踪这些事件如何转换为 HEC 活动图，然后将完成定义为：将该时间区间显示为一个可测量的独立 foreign-call 活动。

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