misc: separate ProfitRegress and TradingCounter from runstat module

The framework will support a lots of complex statistics in the near future, so
we have to separate each of statistic functionalities into independent modules
to keep runstat as clear as possible so that it will be easy to extend runstat
to support other features.

Signed-off-by: Zhengwang Ruan <ruan.zhengwang@gmail.com>