Migrate FindPoco.cmake to cmake_modules

[mitchellwills]

I was looking to potentially use the Poco library in one of my projects and I noticed that class_loader has it's own private copy of FindPoco. Is there any reason for this or can it be migrated to cmake_modules?

[mirzashah]

class_loader was intended originally to be a ROS-agnostic package...but given that it's a ROS catkin package anyway...I'm not sure there's any reason for it anymore. Also at the time, there was no cmake_modules package

[esteve]

Sounds good, I'll submit a PR to https://github.com/ros/cmake_modules/ and move FindPoco.cmake there.

Thanks!